I'm here to tell you that 'Splosion Man is definitely not a joke. It's one of the best 2D platformers in recent memory.
The description above holds true, 'Splosion Man is a lab experiment gone wrong. Now he is made entirely of 'splosions and must A) escape from the Big Science lab and B) seek vengeance on the scientists responsible. He does this by 'sploding, lots of 'sploding. In fact, other than walking, 'sploding is the only action players can take. Don't worry about which face button you press. It will make you 'splode.
"Puzzle sequences resemble a Rube Goldberg machine, or some demented ballet"
The level design is really what makes the game shine, with every section laid out very precisely, requiring perfect timing and quick reflexes, especially in the later levels. When done correctly, puzzle sequences resemble a Rube Goldberg machine, or some demented ballet. Failing, generally, means a quick death and starting again. Thankfully, there are plenty of checkpoints between puzzles, which minimizes frustration (a little).
Even more enjoyable than the single-player campaign, however, is co-op. Rather than simply allowing up to four players to run through the single-player campaign, 'Splosion Man contains an entirely separate co-op campaign, with each level actually requiring that players work together. As a simple example, there are many areas that are too high for a single player to reach, so one player will have to use his 'splosions to boost the other over the edge. Of course, if you're not careful, you might just rocket your partner straight into a pool of lava. And, if you're like me, you might not always do it accidentally. Don't be surprised if you start killing each other just to blow off some steam in between puzzles.
Which brings me to another point: 'Splosion Man is funny. 'Splosion Man himself comes complete with lots of amusing animations, my favorite being him running with arms extended while he makes airplane sounds. He does make a lot of noise too, including lots of nonsensical blabber and even a few weird one-liners (the best probably being "We're done, professionally"). Scientists will run for their lives, or mutter to themselves as they cower, and even the bosses get in on the act. I have to admit I chuckled when the first boss said "Not cool, man!" after being damaged. There are plenty of other funny surprises, including one for Maw fans, but I won't spoil them here.
If 'Splosion Man has a caveat, it's that the game is not for the faint of heart. The later levels can be really brutal, especially in co-op. Getting the timing perfect and synchronized is no simple task, but it's also incredibly rewarding. 'Splosion Man is not an easy game, but it's worth every minute of frustration, even if it's just for a chance to watch the best end credit sequence ever made.
Go buy it.