After playing Microsoft's Impossible Creatures for a while, I've decided that making animals is fun, but not that fun.
If you haven't heard of it, IC is a God-game set in the slick 1930s, that lets you combine real animals and then fight against armies of other genetically mutated creatures.
There are two parts to the game: one, making the creatures (the good part) and; two, using the creatures (the bad part).
I'm happy to say that making creatures is the most fun I've had in a game for a while – it's intuitive, funny and you'll spend hours just checking out all the possible creature combinations. Creating the ultimate monkey army took me well over an hour, and I didn't even notice.
Unfortunately, the same can't be said for the bit where you're actually supposed to use them. Not only is it an RTS, but it's a pretty lame one at that. It's about three years behind the rest of the genre: smart right clicking isn't smart, combat is too fast to be interesting and there's no way to set specific AI routines. This last one is a particular killer as you can't, say, have your flying monkey swoop down and use the 'plague' special ability unless you directly tell it to do so. Try doing this when there are a hundred units fighting it out.
A game series that did get it right is Australian developer SSG's Warlords Battlecry. SSG absolutely nailed what was needed in an RTS: smart resource gathering, broad AI routines (for example, you can automatically set a spell-caster to use spells where relevant, and then default to its weaker melee attack) and great RPG elements. Not 3D? I couldn't care less -- the game wasso streamlined that you didn't have to worry about repetitive clicking and chore-like actions. All you had to worry about was making decisions.
I picked up a copy of Warlords Battlecry 2 (far superior to the original) for less than twenty bucks at a Harvey Norman sale. I strongly recommend checking it out if you actually want to play a good game, rather than a dressed up Mr Potato Head.