Steam cuts up to 50% off game collections for Windows as part of its Holiday Sale. (Some games within the collections are for both Windows and Mac.) With prices starting at $24.99, they're at the lowest price we could find. Sale ends January 5. The collections:

• THQ Collection (Darksiders I & II, Warhammer games, Company of Heroes, more) for $24.99
• Valve Collection (Portal 1 & 2, Counter-Strike: Global Offensive, Half-Life games, more) for $49.99
• SEGA Collection (Total War: Shogun 2, Sonic Generations, Empire: Total War, more) for $69.99
• Indie Super Mega Pack (Bastion, Awesomenauts, LIMBO, Orcs must Die 2, more) for $69.99
• Bethesda Collection (Dishonored, The Elder Scrolls III-V GOTY, Quake I-III, more) for $89.99
• Ubisoft Collection (Assassin's Creed III, I Am Alive, Far Cry 2, more) for $89.99
• 2K Collection (Borderlands 1&2, Civilization V, X-COM games, BioShock, more) for $89.99
• Square Enix Collection (Deus Ex: GOTY, Sleeping Dogs, Tomb Raider, more) for $89.99