When a game is great, we refer to it as a "beer warmer." The genesis of this term? You sit down for an evening of gaming, open a beer, then find yourself so engrossed in the title that the next time you remember to take a sip, the beer's no longer cold. Microsoft has been releasing beer warmers with surprising regularity during this year's Summer of Arcade promotion, and the trend continues with the release of the sublime Trials HD. What makes a motorcycle title—that doesn't even give you the ability to steer—so good?

The case for keeping it simple

In Trials HD, you're on a motorcycle in a 3D world, but you only have to worry about two dimensions. In fact, the only controls you have are a brake, the throttle, and the ability to lean backwards and forwards. That's it. The implementation of physics, especially the interaction between the bike and the game world that results from shifting your center of gravity on the bike, makes up the entirety of the gameplay.

It sounds like a simple concept, but the levels are anything but easy. You'll be flying through warehouses filled with loops, explosions, barely-balanced boards that require split-second timing to cross... every level will give you something new and interesting to interact with as you try to make it to the finish line in the least possible time. The levels are filled with checkpoints, allowing you to restart a particularly nasty jump if you wipe out. The game also keeps you apprised of just how well you're doing in relation to your past attempts.

You can get a bronze medal just by finishing a track, but the real challenge is unlocking the silver and gold medals to unlock new events and the higher difficulty levels.

While the penalty for messing up may be low, the difficulty can be monstrously high. The earlier tracks are fun and allow you to grasp the subtleties of play, but very soon you'll be white-knuckling your way through some very tricky—not to mention clever—tracks that operate almost like puzzles. There are also a selection of physics-based minigames to keep you busy, including a bizarre pinball-like game that has you being slammed around the level on giant flippers.

While it may take some effort to unlock all these minigames, they're worth it, especially a mode where you are forced to "aim" your bike around obstacles and through hoops while a rocket engine allows you to fly. Realism is not a virtue of Trials HD.

The game also sports a track editor so you can create and share your own levels, and the leaderboards will provide a powerful incentive to continue honing your skills even if you're man or woman enough to finish all the tracks. Although there is no multiplayer, this is a game with a high show-off factor; you may find yourself inviting friends over to try to beat each other's times or to simply show off tricks and stunts you've perfected.

Trials HD may be based on an older PC game—one that's still worth tracking down if you're reading this and don't have a 360—but the updated graphics and online features of the Xbox Live game make this the best release of Trials yet. If everyone reaches for their drink at the end of each track... well, that just means the game is doing something very right.

Trials HD is available now on the Xbox Live Arcade for 1,200 points, or $15.

During this year's Summer of Arcade, fresh games rule

While many people were initially excited about a re-released and spit-polished Marvel vs. Capcom 2 and a re-skinned Turtles in Time this year, the real quality has been in the new or independent games. 'Splosion Man is an amazing take on platforming, Trials HD is the classic example of "one more time" gameplay, and next week Epic brings us Shadow Complex, the Unreal Engine 3-powered Metroid/Castlevania-style title that has gained a deafening buzz since E3.

Bundling a mixture of classics together with new IP and hyping the hell out of both has been a great strategy for this year's Summer of Arcade, and the quality of the games has been far above average. Let's hope the promotion ends with a bang next week.