Cheap Steam games that I can play on a weak laptop?

counter strike

Why not just get some freeware games like Warning Forever and Streets of Rage Remake?

I enjoyed playing Mark of the Ninja, the Binding of Isaac and even TF2 on low settings

How weak is it? Just look at the minimum system requirements for games you think you would like and go from there.

• Papers, Please
• Alien Shooter
• Time, Gentlemen, Please + Ben There, Dan That
• Serious Sam Classic Encounters
• Return to Castle Wolfenstein (+ Wolfenstein 3D)
• Lone Survivor
• Osmos
• Home
• Organ Trail: Director's Cut
• Faster then Light
  etc.

Those are the games that work on pretty much everything

Doom is always good.