Candy Mountain Massacre is interesting on two scores: Technology and imagery.
On the technology side, it's a Shockwave game, but it's true 3D, and remarkably good looking. Not Unreal-engine levels of "good looking," but maybe somewhere around the level of Quake II, which is actually pretty astonishing for a browser-playable game.
It's a first-person shooter, no bones about it; same verbs (run, jump, shoot), same powerups (health and ammo), same win conditions (blow up the bad guys real good). But what makes it different, and amusing, is the imagery.
Apparently, this particular game of violence with guns is set in Candy Land. Okay, not "Candy Land(tm)", the trademarked and copyright property of Hasbro, Inc.; the structures are not recognizable as those on the Candy Land board, and the developers are careful to ensure that none of the characters in the game look too close to the beloved characters of that perennial game. (Can't be too beloved, as I don't actually remember any of their names offhand, but I'm sure I'd recognize that candy-cane doofus and that silly king.)
But nod nod, wink wink, it's pretty obvious what the developers are about. You wade through chocolate rivers and pass gingerbread houses; the enemies you shoot are deranged rabbits and Mad Hatters and the like. There's some spurious backstory about how the sweet critters of "Candy Mountain" have been taken over by evil whatsis, but you know, in an FPS, things exist for you to blow them away. There's a level of humor here -- not Doom's monsters from hell, but brightly colored things out of the canonical children's game -- although it is kind of a one-note joke.
Still, for a web game, which you're only going to play for a short period anyway, a one-note joke will do.
You have a choice of three characters (all female)--cosplay, "exterminator" and "black ops". Not right up the Candy Land alley, but cute.
As for the gameplay itself--what do you want? It's a straightforward first-person shooter. Nothing real innovative, but it's entertaining, and it's free.