Does steam render pirate games unplayable?

I have a bunch of illegal games on my computer, and i was wondering what would happen if i downloaded steam? Would it make them unplayable? I only have single player games like crysis, far cry 2,etc..., incase that has anything to do with it. The game i want to play on steam is tf2, which my brother bought. In short, does steam ruin these games?

Don't give me crap about piracy.Does steam render pirate games unplayable?
Nope you can still play all your other games. Legal or not.

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