Excit is a pretty straighforward puzzle game, with a basic principle that you've probably seen before. However, it does a very good job implementing the game, with interesting and tricky puzzles, and a very clever visual aesthetic, which overall make it a pretty solid game.
The basic gameplay is quite simple: you move on a rectangular grid, with some walls scattered around it, and the object is to move to the exit. However, the catch is, once you press the arrow key to start moving in a certain direction, you keep moving in that direction until you hit a wall. (If you should happen to fly off the screen, you fail and have to restart.) Like I said, you probably have seen this mechanic somewhere before, but Excit does a good job making solid puzzles with it. In addition to the basic walls, there's a variety of other elements -- curved blocks, one-way gates, teleporters, locks and keys, and so forth. You might think that you could solve these puzzles by logic, but actually working backwards is pretty unfruitful -- there's just too many possibilities too quickly. So there's a lot of trial and error involved. This can get frustrating in some of the more complicated later levels, especially when you make a fair amount of progress but then make a wrong step and have to start over again without quite remembering what you did. (Also, since many of the levels feature more locks than keys, or things that have to be done in a very specific order, it's relatively easy to get yourself into a corner even if you are careful about not going off the edge.) If just getting to the exit isn't enough of a challenge, you can also collect MIS logos (I thought this was just a reference to the IT feel of the game, but apparently it's the name of the company that makes the game, in a rather amusing coincidence) for an extra bonus; some of these are quite easy, but some are nearly impossible. (Fortunately, you don't have to collect all of them.)
The visual design of the game is very clever -- it looks nearly identical to an Excel spreadsheet, which gives the game a nice feel. The elements are also a little bit dynamic (you bounce a little bit when you hit walls, teleporters shimmer, and so forth), which also makes the game feel a lot better than if it were entirely static. There's no music, and the sounds are very basic indeed.
The game does have one very large flaw, though; if it had come out today, it probably wouldn't get badges because of it. The game doesn't have any intrinsic save ability, but it does give you passwords for each level. However, Kongregate clearly couldn't award you a badge based on that, since you could have gotten the password from somewhere else. Consequently, in order to get the hard badge, you have to play through all 30 levels (and collect 60 MIS logos, which fortunately is not all of them) in one sitting, which is not fun at all. The game would be vastly better with a true save feature so that you don't have to play it all at once. There's also one small additional flaw with being on Kongregate. In its native resolution, you see the full spreadsheet; this means that you can use the row numbers to tell if something is actually on the same row as you (a surprisingly difficult task for things far apart on the board). However, the Kongregate version is slightly clipped, so the row numbers on the left are eliminated. This makes it a little trickier to navigate.
Overall, Excit is a well-designed puzzle game; while it can certainly get frustrating at times, the levels are carefully crafted and challenging without being horribly unfair. Still, that lack of a save feature is a really frustrating omission; even without the consideration badges, a game which can save for itself is much preferable to a game where you have to write down a password all the time.