I’m going to refer to these by number, the top one being 1, and the bottom one being 8.
2 and 4, having the Space Invader sprites, felt too retro to me.
3, with Chief, feels too modern and perhaps alienating. My bias here is I don’t like Halo… at all.
5 really popped out to me, because it has the primary colors (which happen to be my favorite, especially when shown together). It also has a video game related image, the joystick, which imo, relates to retro gaming AND modern gaming (Atari = Street Fighter).
1, 6, 7 and 8 (with the possible exception of 6) are boring to me, and don’t have an image that is easily associated with gaming.
5 OR BUST! Primary colors, widely associated logo, pentagram… that shit makes my penis hard.
EDIT: Though, on number 5, I would like to see the ball top blue instead of red. Seems like it would add good contrast, which I think is important for catching the eye.
EDIT 2: 5 also seems to be the most concise and size efficient logo. 1 and 6, having backgrounds, would either clash with whatever background you have for the site, or would obligate you to design your site with that background. 7 and 8 are not only big, but boring. Only problem I have with 5 is the simplicity of the font. Then again, maybe having too flashy a font would be bad. I like Planet Kosmos personally. Maybe some shadow drop or emboss kinda stuff would set it off.