This game is pretty old, but few people talk about it, and it's one of my favorite WiiWare games, so I wanted to give it a little more attention.
The story is ... well, don't know. I skipped it. Who cares? But the game itself is one you surely wouldn't want to skip. This is classic Contra. You've got around five or six levels, all with awesome music, graphics and the challenge you expect from the series. The game looks like a 16-bit game, but with slightly higher res textures to make it look a little more modern, and prettier. There's also some very slight 3D going on. It's one very pretty game - it goes for the Retro look, but you know it couldn't have been done on an SNES. Music is great too, and the first level features an awesome remixed version of the Jungle level from the first Contra game to get you in the mood. There's slight voice acting, too, which is nice.
The game is pretty short, but it's meant for multiple play-throughs. There's no saving feature, and it can be easily beat in one sitting. The idea is to try and go for the high score. You can also mess around with the difficulty settings; you can choose between Easy, Normal, Hard, and you can unlock a Nightmare difficulty. You can also give yourself 3, 5 or 7 lives. This helps the replay value, and also it lets less-skilled players beat and enjoy the game. I truly believe anyone can beat this in Easy with 7 lives - it's pretty easy. But good luck beating it in Hard with 3 lives. You'll spend a while trying to do that. There's also a new character to unlock, but I don't care - Bill is where it's at.
This is how you make a traditional game on WiiWare. If you're not going for a quirky, unique design like World of Goo for instance, you can't do much better than Contra Rebirth. It's short, but good fun every time, and great for quick bursts of play. Pick it up, kill some aliens, put it down. You could do much worse than this.
@X-pert74 I own SS but I cannot stand the music. I also hate the robots and stuff. It was okay through a bit of 3 but past that it was stupid. I like my aliens/humans or whatever they were in the majority of the old games.
@Zero You haven't tried the Challenge mode? That's a significant chunk of the gameplay Contra 4 has to offer. Along with having some cool trials to go through, you can unlock stuff like new playable characters or emulated versions of the two NES Contras.
EDIT: @carlosrox I liked the music a great deal, but to each their own.