Video Game spinoffs aren't actually as common as you might think. Sure, games have tons of sequels, but those don't really count, and mashups like Marvel vs. Capcom or Super Smash Bros. are in a category of their own. To be a spinoff, a game has to be totally separate from the main series, with a totally separate story or set of mechanics that is still somehow related to the original line. Since the majority of the game-playing populace out there reacts negatively when their favorite franchise's formula is altered, most of these games fail. However, there are still some spinoff gems out there that have gone down as great games in their own right.
You'll find that there are a lot of Mario games on this list, and for good reason. Mario has easily had the most spinoff games of any franchise in video game history. While this means that he has had his fair share of crappy spinoffs, it also means that many of them were solid quality games. Perhaps his most famous spinoff series featured his evil twin Wario, who eventually became famous enough to get his own franchise. It all started with Wario Land on the Game Boy, but from there it exploded into new Wario-themed game after new Wario-themed game. Now Warioware is easily one of the best handheld and party games out there. The king of greed himself would be proud.
Many of you have never played Typing of the Dead before, and, quite frankly, you should be ashamed. This House of the Dead spinoff is ludicrously fun, perhaps more fun than the light gun game that it was originally based off. The premise is simple: type fast and zombies will die. To this day, you can see multiplayer Typing of the Dead setups at gaming conventions everywhere, even gaming conventions that don't have plain old House of the Dead setups. Not only will this game make you a better typist, it will also make you thirst for undead slaughter like you never have before.
Dead or Alive Xtreme Beach Volleyball was actually a magnificent innovation in the world of games. It took all the famous females from one of the best known fighting game franchise and made them strip down to bikinis in order to show off their—er, volleyball skills. The game sold very well to the young male gamer demographic. I wonder why…
Demon's Crest was a magnificent platformer for the SNES (and Gameboy if you count Gargoyle's Quest) that put you in control of Firebrand, the red devil from Ghosts and Goblins. It added RPG elements to the platforming gameplay, and it was loads of fun. Firebrand got tons of different breath weapons and was able to transform into different types of gargoyles. The bosses were larger than life, the platforming was extremely fun, and the music was really really good. If you are wondering why Firebrand got into Marvel vs. Capcom 3, well, this is why.
Old timers like me know that the only true Donkey Kong is a game about a man climbing a construction site in an attempt to reach a giant gorilla that kidnapped his girlfriend. However, you young'uns might remember the big DK in his platforming spin-off, Donkey Kong Country. The DK Country games were all the rage back in the SNES days, and they were some of the most difficult 2D platformers to come out in that generation. They sort of faded when the age of 3D graphics came about, but we remembered them fondly enough that we saw a reboot in the Wii's Donkey Kong country returns. There simply aren't many game spinoffs that are popular enough to get reboots.