BIG BUDGETS and expansive worlds are fun, but I'm increasingly realizing that the games I return to over and over again are those that hinge on a single, well-articulated mechanic. Portal, for instance, is an incredibly simple game focused on using the titular portals to solve various puzzles. Sure, there's a clever story thrown in there, but the game's lasting appeal is in its simplicity.

Likewise, today's review subject, Trials Evolution. This is a game about riding a motorcycle to the right until you hit the finish line. Period. Exclamation point. That's all you do. However, the true appeal of the game is in its details.

That bit about driving to the right, though accurate, is really only half the gameplay. While driving you're tasked with leaning your character to the left and right, lest your bike flip over. Initially, you'll struggle simply to stay on the motorcycle, but once you get good, you'll find yourself tweaking your positioning in an effort to speed through the tracks as quickly as possible. Faster finishes mean bigger rewards, but more importantly, they also mean a new best time that your Xbox Live friends can compete against. It's a simple system, but it's also intensely addictive.

Additionally, developer RedLynx packed Trials Evolution with so many extra gameplay modes, unlockable extras and customization options that even the best riders will spend months trying to see everything available. Then, assuming they manage that, there's a totally gratis track editor that not only allows players to create new tracks, but also lets them share their creations on Xbox Live. In effect, it gives the game an infinite, free supply of downloadable content, and there are already a huge number of fantastic fan-made tracks available. Oh, and did I mention that Trials Evolution is only $15? The game has far more replayability than the majority of $60 titles. For a quarter of that price, it's a steal.