A true arcade classic and a true classic on the Genesis as well. While its a bit scaled down when compared directly with the Arcade version's graphics/sound, however, the soundtrack to the Genesis/Megadrive is superior. The individual who composed the music for this game did a very good job. Its also about one of the few areas where this version beats the SNES version which has really good graphics for a 16-bit version. This game is very easy to figure out, particularly the first few stages. The third stage is a bit tougher, just rememmber to focus on the HK air's (flying machines) and not the endoskeletons. You have a decent amount of weapons in this game, the first half of the game you have a particle beam rifle that you can upgrade with plasma energization, where in the later levels you could upgrade your basic rapid fire weapon to a gattling gun. Your secondary weapon also changes from a rocket launcher in the begining of the game to a shotgun. This game is a lot of fun, and its really fun with 2 players. The only really flaw of this game is it is FREAKIN hard. There are a few stages that I swear are impossible or, just so hard I haven't had the time or patience to figure out why I haven't beatin it yet. Though this is a really awesome game, and so is its SNES counterpart.