What better way to end a stressful day of hd/030 patching than a hard puzzle game? :P
I just learnt today that the 6th installment is out, and played it. As usual, it's full of logical puzzles with little or no hints, so you have to figure most of them by yourself. Interesting storyline too (it's not needed to enjoy the games, but it gives them coherence).
I hope I didn't intimidate you enough not to try it! The basement, The lighthouse, The loop, The lab, The root, FLF, Zero, The edge, The core, The plan, The temple and the last in the series: The exit.