Ah, Wario Land II. The Game Boy Color was such an amazing era. . . . Most people I know don't want to try this game because (1) they hate Wario or (2) they've played Wario Land 4 and think it must be a lot better. It's not. In fact, Wario Land 4 is a total piece of crap compared to the rest of the series.
In Wario Land II, you play as, no duh, Wario. Yes, that same character who nowadays is always acting like a total moron and acting inappropriately. That is the Wario that I hate. This is the Wario that I love.
You travel through five worlds, each consisting of five levels, to get to the lair of the evil Captain Syrup, so you can steal back the treasure that she stole from you. Yes, over the years Wario has stayed just as greedy as he was back when this game was made, but it's one of the few parts of his personality that have carried over time.
There are enemies, and they can do different things to Wario. Enemies sometimes cripple Wario in some ways, and other times it seems like they give him a power-up. Sometimes you can get to other places that otherwise couldn't from being "crippled" by certain enemies' attacks.
Wario Land II is long, challenging, and literally jam-packed with secrets. There are as many secret levels are there are normal levels, and the secret exits and passageways aren't easy to find at all. For an unexperienced player, you could spend literally months trying to find all of the secrets in this game. This is why it is one of my favorite games ever made for any system ever. Nothing, no Wario Land 4, no Call of Duty: Black Ops, can beat this game in my standards, unless there's another 2D platformer that goes even deeper.
-Very long game, all secrets included
-Jam-packed with hard-to-find secrets
-Super addicting gameplay
-One of the best games ever made
-If you've 100% completed the game too many times, it's not quite as awesome (but it's still awesome nonetheless)
-Some enemies can get pretty annoying
-Sometimes you spend forever trying to get to a secret passage, and then you finally do, and find out you're not suppose to get there that way (but oh well, you got there anyway!)