I got a bit discouraged after several people already made their own math quizzes. Making it now would be a bit trite, maybe other time when you all forget about it. I haven't seen a game music puzzle in a while though, and these are always nice, so here is mine.

Rules:

1. NO SHARING ANSWERS
2. Do not forget Rule 1.

No contribution required, giveaways end on February 11th 2012, 11:00 am UCT+1. I will decide whether or not to give hints later, depending on how many people will have difficulties.

http://www.itstoohard.com/puzzle/xwCqi1vH
New version. Old version got deleted after someone came upon a way to find answers easier; luckily he was fair and informed me about it.
EDIT: I don't feel like making the third version, but the link to 20th question doesn't work. Click here for that video.

HINTS. If there are still no solvers later, additional hints will be provided.

1. Eggscellent game from a really giddy series. Said series was popular in the UK (where it was made) and Ex-Eastern Block countries, but not much in the US from what I gather.
2. Green animal formerly classified as a rodent solves his problems with a big gun. You can also play as another, mentally unstable totally-not-rodent.
3. RPG based on a very popular sci-fi franchise. Has MMO 'sequel' that wasn't welcomed warmly.
4. Cows are weapons of mass destruction. Uncanny protagonist that shouldn't even have limbs... he technically doesn't, but it's not like he lets that stop him.
5. RTS. War. War in the far future. War war war war war. Did I mention war? There is only war. Grimdark. That's all you need to know.
6. Sci-fi RPG/FPS hybrid. Most people would recognize the game from main menu music. This is from credits and not as many people recognize it, even though this tune is nice too. What a shame.
7. Adventure game where you're looking for your dad. Ghosts, but no horror. Not a very subtle product placement of a handheld this was released on. (DS)
8. Kid general who doesn't know what airport is. War has never been this colorful and fun.
9. Platformer, a spin-off of a famous logic game. Series this is based on features creatures named after real-life animals that look nothing like them.
10. Appeared in several Sonic compilations, but has nothing to do with Sonic.
11. Spin-off from a series popular on NES. Robots. One of the bosses is named after a musical term.
12. Series known for shirtless heroes. This installment is the first one where the shirtless hero is optional.
13. Sega does what Nintendoes too, and Nintendoes RPGs. Mesh of sci-fi and fantasy. Contains an archaic spelling in the title.
14. One series that just didn't want to die. This entry didn't make it out of Japan (officially) until many years later as a remake.
15. "Speed up! Laser! Option!" Moai heads in space!
16. Totally-not-Indiana-Jones searching for a treasure of life. Aliens. Extremely difficult - in the original freeware version you had to buy (for in-game money of course) ability to save!
17. Arcade cult classic, you might know it for one of the sequels on X360. Contains dangerous amounts of bees. Some are even on fire!
18. Your deities are gone. Now you have to climb up a tower. Prequel.
19. Evil corporation named after Microsoft wants to conquer the universe. It's up to you to stop them in your trusty spacecraft. Currently freeware.
20. Shoot 'em up. Pumpkins. Bunnygirls on motorcycles. Things with guns, girls with guns, guns with guns. It mentions guns in the title, if you missed the fact it contains guns.