But real was exactly what UGOBE Inc. had in mind when the company created this $350 baby dino named Pleo. This robot isn’t referred to as such; instead, UGOBE calls Pleo a “life form” because unlike most robots that are designed to follow a specific command or algorithm, Pleo alters its behavior as it adapts to its surroundings including sights, sounds and touch. And it’s designed to move and act in ways that seem very much like a real animal.

These responsive qualities have earned Pleo quite a bit of attention, and the two years between when the product was first announced and when it became available only added to the anticipatory hype. Now, after three delays in the past two years and numerous back orders, Pleo is available from www.pleoworld.com. (UGOBE says that many of the product’s delays were caused by trying to get Pleo’s battery just right.)

In short, I found Pleo to be a fun and interesting robot/life form. Though Pleo’s reactions and movements are endearing, many of them run together after a while with only subtle differences, especially compared with fast-paced videogames. Pleo’s tricks were entertaining early on, but, in time, many of them blended together, rarely surprising me.

Pleo’s battery is still a major drawback. It’s rechargeable, but only lasts for around an hour of active play before it must be removed and placed in a holder for three hours of recharging. This frustrating fact means you can’t turn Pleo on to roam the house with you all day like a dog or cat. Instead, your time with this creature has to be more specifically planned, causing interactions with it to feel less genuine. My Pleo’s battery lasted for an hour and 40 minutes, including moments when he drifted in and out of sleep.

Though UGOBE sent me two rechargeable batteries so I could more quickly continue using Pleo, the company won’t start selling extra batteries until June (at the latest) for $50 each. This means waiting for hours between Pleo playtimes.

It’s hard to discuss autonomous robots without remembering Sony Corp.’s attempt in the same category: the $2,500 AIBO released in 1999, which was eventually discontinued. More recently, iRobot Corp. has gained attention for its robots, which perform household duties like vacuuming and washing floors.

The Pleo, animated in part by 14 motors, appears to evolve according to how it is treated.

To keep Pleo fresh, UGOBE plans to release a PDK — Pleo Developer’s Kit — later this year, allowing others to create programs that will run on Pleo if downloaded from the Pleo Web site and transferred to the creature. A memory card slot and USB port on Pleo’s underbelly will enable these transfers.

As for now, two programs developed by UGOBE can be downloaded. One program lets Pleo act like a watchdog — guttural growl, loud bark and all — and the other gives it the ability to sing Jingle Bells. I tried the former, and my Pleo performed marvelously, sitting still and only howling when something moved in front of him.

This baby dinosaur has reptile-like, rubbery skin enhanced by multiple sensors. Its back is decorated with green patterns, and its large eyes are a beautiful blue. Pleo’s guts include 14 motors, 38 sensors and a microprocessor. Infrared detectors are hidden in Pleo’s nose and mouth, and a color camera detects light, motion and objects to help it navigate.

Pleo grows through three phases: hatchling, infant and juvenile. As a hatchling, my Pleo sniffed around a lot, unsure of its surroundings or how to use its legs and tail, before giving up and napping again (yes, Pleo snores). The more I talked to and touched Pleo, the faster he adjusted out of the hatchling phase, which is expected according to UGOBE.

People who walked by my office stopped to marvel at Pleo’s sweet nature, and when I brought him home, friends melted with emotion. I watched as they initially looked at Pleo like just another toy dinosaur until realizing that he responded to them, and then they each wanted to take turns playing with him.

Stroking Pleo from the tip of his nose to the end of his tail induced a purring sound; touching sensors on the bottoms of his feet caused him to wriggle around and make laugh-like noises; and holding him to my chest and rubbing his back like a baby put Pleo right to sleep, indicated by heavy breathing and even a burp here or there. I spoiled my Pleo with attention, which seemed to make him more social and friendly but also a little bratty when he didn’t get attention (he showed his frustration with loud moans).

I didn’t get to test this, but one Pleo can sense when another Pleo is nearby using infrared sensors in the nose and mouth. UGOBE says the sensors in one Pleo can trigger actions in another based on moods, including singing and howling.

Pleo can be a troublemaker. One of the times I left him unattended, I returned to find Pleo trying to gnaw on my loveseat, despite lacking a set of teeth. Another time, Pleo wandered my desk, wrinkling up papers and crying loudly while I was on a conference call.

UGOBE’s pleoworld.com site includes an online community, though you don’t need a Pleo to get involved. The community is just a social networking site where anyone can discuss the device and/or robotics. This differs from sites like Webkinz, where kids input codes found on stuffed animals to register and care for digital versions of their creatures.

Pleo’s poor battery life is a frustrating hurdle that fans will keep butting up against. But UGOBE’s plans to introduce downloadable updates for this robot and to let others create programs for Pleo may give new life to this clever creature.

• Email mossbergsolution@wsj.com

Even people utterly uninterested in videogames know by now that two new game machines have arrived this month to lure holiday shopping dollars out of consumers’ wallets. One is the long-anticipated PlayStation 3 from the videogame leader, Sony Corp. The other is the more obscure Wii, from the videogame pioneer, Nintendo Co. Both are going up against the year-old Xbox 360 from Microsoft Corp.

Like the Xbox, the PS3 and the Wii bear little resemblance to the toylike game consoles of the 1980s and 1990s. They are powerful computers that have been optimized for graphics and sound. And, like the Xbox, the two new contenders can handle multimedia and can connect to the Internet.

We’ve been testing the two newcomers, with help from four volunteers, three men and a woman, all in their 20s, most of whom have extensive game-playing experience. We tried a selection of games for each.

Sony’s PlayStation 3 (left) and Nintendo’s Wii (right).

These two new game machines couldn’t be more different. The PlayStation 3 is a bulky, shiny black box that costs $600, or $500 for a somewhat stripped-down model. That’s up to $200 more than the Xbox 360, and about what you’d spend on a basic Windows computer. The PS3 includes a hard disk, a networking port, Wi-Fi wireless networking, and playback of DVDs and CDs. It produces high-definition video. In fact, the PS3 can also play a next-generation, high-definition movie disk, called Blu-ray.

The Wii is a small, thin white box that costs just $250 and has much wimpier specs than the Sony. It does have Wi-Fi, but it lacks a hard disk, a networking port, and the ability to play DVDs or CDs, let alone Blu-ray disks. It cannot produce high-definition video. It has fewer ports and connectors.

Yet, in our tests, we found the more modest Wii to be the more exciting, fun and satisfying of the two new game machines. We and our four volunteer testers were impressed by the rich, realistic graphics and intricate game play in some of the half-dozen PS3 games we tried. By contrast, we all agreed that the graphics on the Wii ranged from dated to cheesy.

But the Wii won our hearts for one reason: It uses a wireless controller that can detect your arm and hand motions and transfer them to the screen, so that you can physically control the action. This opens up huge possibilities. In sports games, you can actually swing a baseball bat or tennis racket or golf club. In adventure games, you can slash a sword through the air or throw a punch. You make pretty much the same motions, using your full arm and hand, that you’d make with the real objects.

With the Wii, you don’t sit on the couch and just press buttons. You typically stand. You get a workout. In fact the Wii controller, a slim rectangular gadget that looks like a TV remote control, has a wrist strap to prevent it from being hurled across the room while you are, say, serving in tennis. The controller also has a small built-in speaker and it transmits vibrations to make the play more realistic. There are already reports of people complaining of sore elbows and wrists from hours of Wii play. Our testers were initially amazed that they felt a little winded and sore after hours in front of the Wii.

To show off these capabilities, every Wii comes with a free disk called Wii Sports that includes simple, basic sports games — tennis, baseball, golf, bowling, and boxing. These aren’t fully realized games; they are more like demonstrations. The graphics are crude and the games lack multiple levels of difficulty. But they are terrific fun. One of our testers, a college athlete who is bored by standard videogames, said they gave her the first opportunity ever to feel successful at a videogame.

We assume some clever game developer can produce more sophisticated versions of these sports games, and of other types of games that make full use of the Wii controller. There are also likely to be specialized controllers that can take advantage of the Wii’s motion sensitivity.

The PS3’s controller, which resembles the one on the previous-generation PlayStation 2, also has some motion sensitivity. But it seems much more limited, and the controller doesn’t vibrate.

The two products are clearly aimed at different audiences. While the PS3 has a lot of multimedia features, it is really for hard-core gamers with deep pockets (or with parents with deep pockets) — the folks who spend days mastering all the levels and secrets of a complex game.

The Wii is for casual game players, including younger kids and older adults who find the complexity and finger skills required for the PlayStation and Xbox to be intimidating. Even adventure games and racing games on the Wii seem easier to get into than similar titles on the PS3.

Left: Two people seen standing while they use the Nintendo Wii’s motion-sensor remotes to play games. Right: Screen views of a Wii tennis match show on-screen players mimicking motions of the wireless controllers.

In addition to Wii Sports, we tested and enjoyed two other Wii titles — “The Legend of Zelda: Twilight Princess,” an adventure game; and “Excite Truck,” a driving game. In the former, the controller can be swung like a sword. In the latter, you can move it to steer. We also ran a simple slideshow on the Wii by inserting a memory card from a digital camera.

The Wii can also play a selection of older Nintendo games, such as Super Mario and Donkey Kong. You have to buy and download these from the online Wii shop. But we were disappointed that they require the purchase of an extra, old-style controller, which we couldn’t find in either of our local Best Buy or Circuit City stores.

The Wii also has a fun system for creating avatars you can use to represent yourself in various games. They are called “Miis” and you can assign them a wide range of facial features.

The PS3 has some impressive features. All six of us were blown away by the graphics on PS3 titles like “Genji: Days of the Blade,” an action-adventure game set in old Japan; and “Ridge Racer 7,” a car-racing game. We enjoyed the skateboarding game “Tony Hawk’s Project 8,” including the use of the PlayStation controller’s limited-motion sensitivity — though the graphics in that game were much cruder than in the other two.

We also were impressed by the photo slideshow feature on the PS3, which turned photos on a camera memory card we inserted into sharp, vibrant images of snapshot prints fluttering on the screen.

We also watched a high-definition movie on a Blu-ray disk and thought it looked and sounded good.

But none of us felt that the game graphics, or the Blu-ray movie playback, were superior enough to the Xbox 360’s graphics and DVD playback, to justify the PS3’s heftier price. None of our four volunteer testers said they’d buy the PS3 at $600. (The $500 model of the PS3 seemed a bad bargain because it lacks Wi-Fi, which is needed in most homes to connect to the Internet for online game playing.)

In fact, the PS3’s graphics, while better in some cases than what we’d seen on the Xbox, weren’t knock-your-socks-off better. And, to really get the most out of a PS3, especially its Blu-ray disk feature, you need a high-definition TV.

In addition, there were some annoying lapses on the PS3. Setup was long and complicated. Load times for games and for levels within games were slow. Typing is tedious, using an onscreen representation of a cellphone keypad (though you can attach a computer keyboard if you have one.) Just registering for the Internet features seemed to take an eternity.

Plus, the PS3’s wireless controller was a pain. In our tests, it often ran out of juice and had to be plugged in to be recharged. Once plugged in, we were always accidentally disconnecting it, because the cable was too short.

Speaking of cables, they may cost you a bundle on a PS3. It comes with a new-style high-definition connector, called an HDMI jack, that provides the best video on a high-definition TV. But it lacks an HDMI cable, an accessory that can easily cost $100.

For mainstream users, who lack the skill or patience or interest for complex videogames, the Wii is the way to go. For hard-core gamers, the PS3 will be the one you want, but only if you are willing to part with a lot of money.

Write to MossbergSolution@wsj.com

Cardiovascular exercise saves lives. But, for millions of people who need it the most — those who aren’t naturally drawn to physical activity — using a treadmill, stationary bike or elliptical machine has one huge drawback: it’s boring. The timers on those machines seem to move excruciatingly slowly while you grind out your daily fitness regimen.

To combat this boredom, the fitness industry has mainly relied on television in gyms, or encouraged people to use their iPods or other portable music players while on the machines. But, despite these distractions, basic exercise can still be mind-numbingly boring.

The $4,995 Spark by Expresso Fitness Corp. attempts to make exercise more exciting with videogame-like simulation, bike handlebars that move and gear shifting.

Now, a Silicon Valley company has come up with a new idea to enliven cardiovascular workouts. It is turning exercise into a videogame, complete with opponents and scenery. Expresso Fitness Corp. in Sunnyvale, Calif., (www.expressofitness.com) has introduced the Spark — a stationary bike with a built-in computer and flat-panel monitor that allows you to race against virtual riders through a variety of simulated outdoor courses.

Unlike the typical exercise bike, the Spark has movable handlebars to steer you through the three-dimensional virtual trails on its screen, and a gearshift for tackling the many hills you encounter. When you climb a hill on the screen, the pedaling really feels like you’re climbing a hill.

The bike has a built-in TV and built-in music channels, but its key feature is its competitive virtual riding courses, which can be updated by the company over the bike’s built-in Internet connection.

The Spark’s $5,000 price tag plus $225 installation fee and shipping seems like a high price to fend off boredom. But even though the bike was originally designed for use in gyms, the company claims it has been attracting individual buyers as well.

We’ve been testing the Spark for about a week in a spare office near ours that we turned into a temporary gym. Our verdict: the Spark makes stationary bicycling more interesting and challenging, even for average users. But there’s a downside: Most of its courses would be far too difficult and strenuous, and highly discouraging, for the average, out-of-shape users who need it the most. The Spark seems to have been designed by and for athletic bicycling enthusiasts who we assume would rather be outside on real bikes most of the year.

At times we were plain exhausted by the Spark. We represent two age groups — one of us is in his 50s and the other in her 20s — and we both exercise regularly. Even so, most of the Spark’s 26 routes were daunting, leaving us comfortable only on a few of the easiest routes with sparse, low hills. It seemed to be geared toward hardened riders who wouldn’t be concerned that a 31%-grade hill is labeled as a “Basic” trail.

Physically, most parts of the Spark resemble a regular stationary bike, but a few features make it unique. A box housing an 80-gigabyte computer is positioned on the floor near the Spark’s front end, and a handsome 17-inch color LCD screen replaces what would normally be a bare-bones display on a regular exercise bike. A shifting lever on the Spark’s center column adjusts the bike’s resistance, making your workout more or less taxing in accordance with each trail’s terrain.

This bike connects to the Internet using an included wireless router, and Expresso Fitness uses the connection to help you troubleshoot directly with the company in case of problems, which is useful. It also allows the bike to automatically receive and start using new versions of Spark software. A few days into our testing, for example, Expresso introduced a new version of its software, and our bike was automatically updated with an improved interface.

Six channels of music, each with two or three hours of songs, are stored on your computer, including classic rock, oldies and Latin. The bike’s Internet connection comes in handy here, as well, allowing Expresso to change the collection of songs about every two months.

But the Spark’s always-online connection also sends logs of data from your bike back to Expresso Fitness, including the routes that you ride, your cadence numbers during workouts and other data. This left us feeling like our trainer was checking up on us, which might be motivation for some users. We just found it creepy.

We started out on a seemingly simple route named “Evening Bliss.” We admired the lovely scenery as we started pedaling — leafy trees hung down around the bike path, lush green grass spread out in all directions and a purplish-pink sunset stained the sky. But halfway through the route, we’d forgotten about our 3-D surroundings, concentrating more heavily on our cold bottle of water.

A pace rider in a yellow jersey set a difficult pace for us to match, and multiple bicyclists rode along the trail with us. You can get rid of the other riders by pressing a few buttons, but we found that they motivated us to go faster. Likewise, the pacer’s power can be adjusted so that he rides slower or faster; we slowed him down, as keeping up with his moderate pace was near impossible for us.

On another ride called Coastal Run, sheep and coastline make up most of the scenery. As the road wound around bends and turns, we moved our bike handles in the right direction to stay in the middle of the trail. Unlike videogames where your bike or car can veer off the road or take out other people, the Spark’s simulated routes will only slow you down if you near the roadside and other riders just disappear when you ride over them.

The display screen on the Spark was helpful, showing a horizontal scale of our power, heart rate (determined by hand sensors) and elevation throughout each route. Wireless Polar heart-rate monitors that strap around your chest are also compatible with the Spark, and their data show on-screen. Speed, calories and the pacer’s time in relation to yours are displayed as well.

But we were never asked to enter our weight or age, information required by many average fitness machines before you begin so as to more specifically determine your results.

Expresso says that your skill level will improve as you use the bike more, which we admit might have happened if we had more dutifully stuck to our biking regimen during the week. But we couldn’t help but think that the average person — not to mention a severely overweight person — would be intimidated by the Spark’s rather difficult “Basic” routes. Eighteen other trails make up the Moderate, Challenging and Extreme routes, with names like “Oh Mama” and “Gut Buster.” We couldn’t imagine anyone with a gut in need of busting trying the latter route.

Because the Spark is online, it can always be changed and improved, and Expresso Fitness says it listens carefully to user feedback. We hope it will listen to users who aren’t bicycling enthusiasts, as well, in order to make this technology-enhanced workout more approachable for all types of people.

• Email: MossbergSolution@wsj.com