Some games pare down a core idea to something really simple and elegant, cutting everything else away until one main bit of gameplay shines through. Canabalt is probably the perfect example of that recently -- it's just one core mechanic, done very, very well. But other games go the other direction: they add on system after system after system, and the art isn't in cutting things away, but it's in joining things together, juggling all kinds of balls and knives and torches, and yet still keeping the gameplay accessible and interesting. The recently released (and strangely named) 10000000 is of the second kind: It's a game with a ton of different things going on, but its charm is that even with so much happening, you can still "get it".
Essentially, the game is a match-3 title: You can slide various tiles around, trying to match up three or more of them together. But it's also got a very in-depth RPG layer on top of it -- your character runs across the top of the screen, fighting monsters, unlocking chests, and trying to repair your castle (earning up to 10,000,000 points, which is where the game's name comes from). The gameplay's balanced between what's happening with your character at the top of the screen, and the effects of what you're matching on the tiles below. There's also loot, and skills, and a meta-mechanic that has you repairing doors to open up stages, and even bosses to fight as you race through timed dungeons.
It's complicated, and the biggest problem with 10000000 is that it never backs down -- you need to keep a lot of systems moving at the same time, and it's not always clear where your attention should go. But there is a nice tutorial, and the stages do smartly ramp you up in difficulty, so the RPG elements keep you feeling rewarded, even when you lose track of what you're doing. The excellent old-school graphics and music deserve a mention as well -- they look really great and retro, and the aesthetic adds a lot to the old-school arcade feel.
10000000 is a really interesting title; it could probably have been pared down just a little bit, but the game's designers do deserve praise for including what seems like every system they could think of, and juggling them as adeptly as possible. The game is available right now as a universal build for $1.99.