Don't be too harsh on yourself! The easiest way to play is to print/draw a map and to use a couple of tokens (buttons, coins, whatever) to play physically. Digital solutions may include tabletop simulators such as Owlbear Rodeo (free). It really boils down to try and repeat each level without having to remember anything too difficult.
But yeah, I am a huge fan of Portal series as well as old school stealth games. Maybe I cranked the difficulty to 11 at some points.