RAMbots is an Icehouse game design by Kory Heath. It is a programming game, in which you design short programs that determine what your RAMbot does as it races around the board trying to tag goals, steal pieces from other players, and cause general mayhem. It has been compared to RoboRally, but not having played RoboRally, I can't really speak to that comparison. It's a fun, chaotic game that works well for 2 to 4 players.
Since it's an Icehouse game, there's not really much to say about the components. You need the four standard Icehouse colors (Red, Yellow, Green and Blue), a chessboard that is big enough for the large pieces to lie down in a space, and screens for each of the players to build their programs behind. The Icehouse pieces need to be the stackable kind.
Because the rules are available online, I'll only give a brief overview. The goal of the game is to tag four colored beacons (or other players of the appropriate color) in an order specified by one of your opponents. On each turn, you build a small program consisting of five instructions. Each instruction indicates how your RAMbot will move, and a certain type of beam it will shoot after it moves. Large pieces can move faster, and smal pieces move slower. The beam powers are attack (allows you to steal a piece from a RAMbot that you hit), pull a piece towards you, push a piece away from you, and activate a piece (stand it upright, which activates it for scoring). Once everyone is done programming, they reveal their programs simultaneously and begin executing them. Each instruction has a priority; small pieces have high priority, while large pieces have low priority. If there is a tie for size, then the precedence stack determines which color has priority; if there's still a tie, the precedence stack will determine which player has priority based on their color (at the end of each turn, the precedence stack rotates, so no player gets an unfair advantage). Once one instruction has been executed, it is put back into his code pool, and his next instruction is considered. This way, if you use all high-priority instructions, you can execute all of your code before anyone else has a chance to run; this is balanced by the fact that the smaller pieces move you less, so it's hard to get where you need to go with small pieces. While pieces are moving, they may ram other RAMbots or the goal beacons, which may allow them to steal pieces from the other players and complete their goals. Once you have tagged all of the beacons in the specified order, you win.
The simultaneous movement makes this game very chaotic. Because all of the goal beacons are near the middle of the board, there's a big rush to the center, which leads to lots of ramming, pushing, tagging, and so on. When people ram each other they push each other and steal pieces, they push and pull the beacons, and generally get in each others way. This leads to a fun, light game with a lot of "argh, I can't believe you did that" moments (and the occasional "argh, I meant to play this piece, not that one"). There is a good deal of room for strategy, however, because at any time you know what pieces everyone else has to work with, and you can make sure your instructions are executed correctly before anyone else moves by playing high-priority instructions. There are some real tradeoffs here, because high priority instructions don't let you move as much as low priority ones, so you may lose the race to a crucial piece, and also, if you get there first, someone might come up behind you and ram you.
I find that there are some things that can help make games fun, but lead to the game being broken, that are present in RAMbots just enough to make it fun but not enough to make it broken. For instance, in RAMbots the rich get richer; as you complete goals and ram other bots, you collect more pieces to program with, but this is not an overwhelming advantage. People have lost all but two of their pieces on the first turn, and still managed to come back and win the game. It's also a multiplayer game with the possibility of screwing other players, which can in many games lead to kingmaker and other problems. The chaos and the fact that attacking another player doesn't always help you means that you don't generally run into kingmaker issues. So it manages to have the fun of having the rich get richer and attacking other players, without a lot of the problems.
The game feels fairly different with two players than it does with four (and three is somewhere in between). With two players, there's a good deal more strategy; while there's some chaos due to not knowing what the other player will do, you can generally strategize in ways that account for most possibilites. With four players, chaos reigns supreme, and figuring out how to take advantage of the chaos is essential. Both are fun games, but they feel pretty different.
If you like simultaneous movement, programmed actions, and a good deal of light-hearted chaos, this is a great game. If you get frustrated by not being able to keep track of what your program is going to do, or by the fact that everything you do may be completely screwed up by another player, this game probably isn't for you. It can be a chaotic game with a good dose of strategy, or a strategic game with a good dose of chaos, but on the whole, it's loads of fun.