There's a level, around halfway through Trials HD, where the only route to success involves hopping your little stunt bike between two giant, latticed metal spheres, which roll backward and forward depending on your direction of movement when you're perched on top of them. At first, it's maddening: moving forwards moves you backwards! But after a while you realise that a precise landing allows you to inch backwards at just the right pace to push each sphere forwards without falling off. With the gap reduced, you can hop to safety.
It's a nice idea, nicely done. Trials HD is a motocross game with snazzy 3D visuals but strictly 2D gameplay, and challenges like the metal spheres force you to make the most of the economical controls: accelerator, brake, and the d-pad or stick to adjust your rider's position between pulling back and leaning over the handlebars. You have to manufacture the key flicks, hops and jumps out of nothing but speed and weight distribution. What sticks in the mind about the metal spheres though is that you never see them again in the campaign. Developer RedLynx uses them once, and then ditches them in favour of the next bright idea. It's very Nintendo, that.
In many other respects, Trials belongs to the same category of game as TrackMania. You may only need three controls to move your bike around every level in the game, but the most important buttons are nothing to do with movement: they're the Back button, which resets you to the beginning of the level, and the B button, which drops you to the last checkpoint. The resets are instantaneous, so even if you should land on some explosives, or on your head, and "sustain too much damage to continue" as RedLynx politely describes it, you'll be back to task faster than you can say "temporary blip". As you become obsessed with reducing your level-completion time, and the number of checkpoint-resets to zero, the speed of the reset response gives you no chance to break the cycle of attempts. You just keep playing.
All this was true of the excellent PC version, of course, but the Xbox Live Arcade release narrows the focus. Rather than four game types, the one main solo campaign condenses the lessons of the PC original into more than 50 levels full of clever ideas, spread across a difficulty curve that inclines to match your improving handle on the controls. The discrete "dynamic" levels of the PC game, which introduced rough-and-tumble physics to the environment, are gone, and instead the core levels of the XBLA version have physics-based elements dotted elegantly amongst a majority of static components. The goal remains to get through levels with as few resets and as quickly as possible, but now you earn medals for doing so, and there are also Tournaments, where you have to try and keep the fault numbers and level times down across several stages in sequence. Yikes.
Every level has its own leaderboard, and if you earn a gold medal within a time that puts you in the top 5000 players worldwide, your replay will be made available via the leaderboard. That's the same for everyone else, too. Even if you're 257th on the leaderboard, RedLynx knows that you want to be able to show off your growing mastery to your friends, and, for that matter, that you want to see what sort of tricks your friends are pulling. This was critical to the appeal of the PC version: not only can you observe the best of the best, but you can see the best of your peer group, and riff off one another's discoveries about where it's best to jump, land and flip to establish and preserve momentum. The only slight shame is that you can't download ghosts as well, as you could on the PC. There are fewer Achievements too - a necessity for Xbox Live Arcade games. Offsetting that slightly are on-screen friends scores in regular levels.