Along with free access to Sanctum 2 through Sunday, Steam has Hitman: Absolution for $5 (or a franchise collection for $9) as well as XCOM Declassified for $12. Meanwhile, Amazon offers Black Flag for $30, Max Payne 3 + GTA IV for $8 and BioShock Infinite for $13, GameStop has Arkham Origins for $25, GamersGate has Grid 2 for $7.50 and XCOM: Enemy Unknown is $10 at Get Games. The latest Humble Bundle is focused on audiobooks instead of games, but the site's weekly sale offers six titles for six dollars.

Steam
80 Sanctum 2 Complete Pack $3.74 (85% off -- free access until Sunday)
79 Hitman Collection $8.99 (80% off)
69 The Bureau: XCOM Declassified $12.49 (75% off)
79 Hitman: Absolution $4.99 (80% off)
68 Retro City Rampage $2.99 (80% off)
Syberia Bundle $3.74 (75% off)
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Amazon Digital
85 Assassin's Creed IV Black Flag $29.99 (50% off)
91 BioShock Infinite $13.20 (67% off)
84 Max Payne 3 + GTA IV $7.99 (80% off)
80 Need for Speed: Rivals $29.99 (40% off)
67 SimCity $19.99 (50% off)
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GameStop
73  Batman: Arkham Origins $24.99 (50% off)
81 Lego Marvel Super Heroes $14.99 (50% off)
78 Scribblenauts Unlimited $7.99 (60% off)
Injustice: Gods Among Us Ultimate Edition $19.99 (60% off)
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GamersGate
78  Grid 2 $7.50 (75% off)
81 Grid $5.08 (66% off)
86 Dirt 3 $6.24 (75% off)
77 Total War Rome II $29.98 (50% off)
78 Overlord Complete Pack $6.78 (66% off)
77 Operation Flashpoint Complete $8.48 (66% off)
81 F1 2013 Classic Edition $22.09 (66% off)
86 Mass Effect Trilogy $13.58 (66% off)
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GameFly
88 Total War: Master Collection $22.49 (75% off)
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Get Games
88 XCOM: Enemy Unknown $9.99 (75% off)
78  Heroes of Might and Magic VI Complete Edition $14.99 (70% off)
Blood of the Werewolf $3.99 (60% off)
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Green Man Gaming
25% off select titles via "33M15F-1DGAOD-YLXBYR"
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GOG
60% off Nordic Games releases