Am I the only one who needs a longer category? Any ideas

Community Chambers with a set list of chambers NBH (No Bunny Hopping) Camera Removal/Screen Breaking (Take down all the removable cameras and or smash all the screens in the wheatley portion) Single Player Cooperative (Beat Single Player and Cooperative in a single run. Can't start Cooperative until both partners finish Single Player) Those are my ideas.

r_drawworld 0;r_drawentities 0 r_drawworld 0;r_drawentities 0;gl_clear_randomcolor 1

"All intended solutions", where the rules are made up based on your own opinion and the time doesn't matter :P

Steam Achievments are either done on the SinglePlayer Game and Cooperative Game. Or really stupid/easy to do like flinging 4 times through different portals. Some challenges such as Ratman are interesting though since it is part of the gameplay but not really ran. It would be interesting for such a challenge to determine where are the ratman triggers.

the problem with achievements is, that there is no way to reset them, once u get them

"the problem with achievements is, that there is no way to reset them, once u get them." False, there is a button to reset your Steam Achievments FailFish

where is it... I need to know

Well, there is no official way to reset your Steam achievements: Source: https://support.steampowered.com/kb_article.php?ref=4462-UIOB-0425&l=english

Try SteamAchievmentManager, but it's unofficial and you risk a ban.

If you really want to play the game for longer, try third person.