There are five chapters (The Fish Age, Early Life on Land, The Age of Reptiles, The Ice Age, and Early Man, if I recall correctly), each with its own world map. On the world map, there are sidescrolling levels you enter to proceed through the game, sort of like SuperMarioWorld?. The levels are usually pretty short and not too difficult, though there are some maze levels and some of the bosses can be hard. You kill enemies by biting them, jumping on them, charging them, or kicking them if you happen to be a mammal. The RPG-ish character building element is that when you successfully kill an enemy, it drops meat which heals you and gives you EVO points. You then spend EVO points on evolving your capabilities: armored skin to increase your defense, better tails to increase your jump, etc. (Vegetarians, incidentally, don't evolve in this game: plants will heal you, but don't give you any EVO points; I don't know what that says). The character design choices you can make start off linear, but become steadily less so as you progress through the game. There are also two types of crystals with special effects: a red crystal turns you into a special form not accessible through normal evolution (some of which are quite powerful), and a green crystal allows you to change into any form which you have recorded before, in a buffer intended for that purpose (usually, I use it to change into one of the red crystal forms).
The difficulty of the game is inversely proportional to how much you want to cheese, ala FinalFantasyTactics. Each time you evolve, you get healed, and with enough time expenditure, you can acquire an arbitrarily large amount of EVO points to evolve with. This allows you to outlast any boss or level in the game, provided you can make any progress (decreasing the boss's HP or through the level) at all. If you confine the amount of cheesing you do, the game is actually quite hard. There some bosses with patterns which are hard to deal with: you usually end up trading hits, and they have a lot more hit points than you. Also, a good GameChallenge is to beat the game the game as a reptile (it's hard, trust me).
The game is short, but despite its length, there's a fair amount of hidden stuff. It has a few wimpy "alternate endings," so some of your choices are not completely Communistic. Another amusing point: reading English language words for prehistoric species translated into Japanese and then translated (poorly) back into English (I think my favorite mangling). Play control is pretty bad, and I certainly wouldn't call it a good game, but it's worth a play through or two.--CurtisVinson
I've been meaning to review this game for the longest time, and this node inspired me: http://home.earthlink.net/~itullis/evo.htm. - IanTullis
Ian's review is funnier than mine. Go read it. If I didn't make that clear above, the primary (only?) reason I recommend this game is just because I find it funny.--CurtisVinson
SPOILERS!!!!
The best forms are clearly bird, mammal, and human. Birds can fly, which saves you a lot of pain in several areas, and allows you to find a few secrets which are otherwise inaccessible. Mammals don't have problems with ice, have better HP and defense than birds, coupled with stronger attacks in everything except bite, and can kick. Humans have high HP and defense (at least when they're big) and the strike attack, which has reach without knockback, making it a very effective tool for pummeling anything that you catch in it (the strike attack is very effective at many of the final boss's forms), but unfortunately pretty poor jumping and run speed.
Clearly the ultimate evolved form of life:
Or possibly: