Alright, so lets get into the meat of this thing.
Fun Factor
This game is fun, plain and simple. It has challenging AI that comes in three stages of Easy, Medium and Hard, although Hard requires a BYONDscape subscription that is no longer possible to obtain. That means we only have access to the first two stages. However, Medium is still competent enough that its fun to play against. And if you play with four players then the game becomes so chaotic that losing is a real possibility at each turn and it doesn't matter what difficulty setting the AI is on.
The simplicity of the game means that you won't want to be playing it all day, as its sure to become repetitive after a while. But the depth of strategy, a common feature in Crispy's games, at least insures that each play will be engaging.
Control and Gameplay
The controls are easy and all you'll need is the mouse. When its your turn, you click on the slime that you want to move, and you have two options, you can click on a tile next to the one you have selected and it'll create a new slime on that tile, or you can click on a tile two steps away from the one you've selected and the slime that you have selected will "jump" to that tile. You have to decide if its worthwhile to sacrifice one of your slimes to gain a better foothold in enemy territory.
Graphics and Sound

I wasn't impressed with the choice of colors for the 3rd and 4th players. Dingy yellow and gray? The gray blends in with the background too much. I'd have gone with some yellow, green or purple. I mean, they're slimes right? Isn't green the classic color for slime?
There is no music in the game so you may want to provide your own, but there are some sound effects. You'll hear sloshing and squishing sounds whenever slimes move around, and there's a little victory fanfare that gets played when the game is over. Its not spectacular, but its better than nothing!
Replayability
As I mentioned before, the AI is competent enough that each play through in single player will keep you entertained. Of course, after a while you may start to find kinks in the computer's intelligence that will make it easier to defeat, but as long as you're not playing this game to excess, you'll forget just enough between plays to let it provide a fair challenge. Okay, that's a cheap way of saying the AI could still be better, but I'm sure it IS better if only Hard mode were accessible. Hopefully that will get fixed sometime down the road.
Playing online may well open up a whole new dimension of replayability for this game, but its not something that I've had the privilege to try.
Conclusion
Carpe Slimum lives up to its short hub description of being simple yet complex. The game is not deep enough to keep you engrossed for long hours and, being more or less a casual boardgame, you wouldn't expect this. If you just want to pass some time, then this is a good game to play, and it could certainly be a lot of fun if you have a group of friends who will join you for a game.