The first Game Boy I ever owned was a Game Boy Color, but I didn't have too many games for it and so I didn't play it very much. I didn't really get into portable games until the Game Boy Advance, so I missed out on quite a few good games. For example, I never played any Wario games with the exception of WarioWare titles, so I missed out on the critically acclaimed Wario Land series. When I saw a beat up copy of 2000's Wario Land 3 for the Game Boy Color in the bargain bin at my local used game store for three dollars, it seemed like as good a place to start as any.
Wario Land 3's major strength is the way it takes established platforming mechanics and alters them in bizarre ways. Right away it establishes that Wario is not Mario by having enemies simply be stunned instead of killed from being jumped upon, and the need to be hit with a shoulder charge in order to be dispatched. Also, Wario is immortal. He can be hit and stunned, but he can't die. If it were simply a regular platformer without death it would be boring, but Wario's immortality is the basis of the game, with levels and mechanics built around this concept.
When Wario is hit, he reacts in various ways that allow him to progress through levels. For example, when set on fire, he runs around, and the player is only able to control his jumps for limited amount of time. After he has been on fire for a while, he is completely engulfed in flames and is able to walk around for a while like that. Levels have certain blocks that can only be destroyed by Wario in this flaming state. After being on fire for a while, the flames go out, leaving him comically charred for a few seconds before shaking it off and returning to his normal state. Much of the game is based around similar states that Wario can be put in.
This is great because it encourages the player to think in a completely different way. Normally when I come across a new enemy in a platformer, I am wary of it and don't really want to see what it can do, but with this game I get excited when I see a new enemy because I want it to hit Wario and see what happens. This is complimented by the non-linear level structure, which has branching paths and places that can't be reached right away, requiring backtracking. All of the levels are meant to be played multiple times, which is shown to the player through these out-of-reach places and the game's day/night cycle. Whenever the player leaves a level the game switches between day and night, and the enemies and their behaviors, as well as other details about the level change based upon whether or not the sun is out.
Mostly, Wario Land 3 is an interesting game with a strange charm. Wario isn't a hero, he's a villain that gets into a wacky situation and only really cares about satiating his greed by collecting treasure. I don't know how Wario has went from being a goofy enemy of Mario into a huge franchise, but I'm glad it happened because I don't think Nintendo has another character that would work in a game like this. I mean, a game based entirely around torturing Kirby would just be sick and wrong.