yes, you need to buy the game to do runs. if you join the discord it makes these questions a lot easier to answer
speedrunning a cracked version of portal wouldnt be legal anyway, ive personally played the games for 8 years so i own an actual bought copy of portal
Hi @DoodleSauce, have you heard about Proton? It's a piece of Valve software that allows running Windows-native games in GNU+Linux with a pretty high success rate. Portal runs natively on GNU+Linux with Steamplay, but you might be able to get Build 3420 to work as well with Proton and Wine. Even if you can't, you can still run the game on the current Steampipe version, though some tricks won't be available.
Starting today, runs that require video proof (top 25) and runs beyond that where video is the only form of proof, now require audio, as recording audio for only the game is now a native OBS feature.