Weekend sales on Steam aren't really the main event, more like the undercard, but this weekend? It's a humdinger.
Some seriously good games in there, like...
— Mark of the Ninja is 50% off at $7.49 — BioShock Infinite is 75% off at $9.99 — Outlast is 75% off at $4.99 — Borderlands: The Pre-Sequel is 66% off at $23.09 — Shadow of Mordor is 50% off at $32.99
All prices are in US dollars obviously.
Actually Shadow of Mordor at $32.99 might be the best of the bunch. If you skipped that one on release it might be worth a bash. Great game, especially if you just got done with Batman: Arkham Knight and you're looking for something a little bit similar.