Game dealers have started celebrating Halloween a few days early with savings on Skyrim, BioShock Infinite, Metro: Last Light, Dark Souls, XCOM, Tomb Raider and more. Max Payne 3 and The Walking Dead at Amazon seem like particularly decent buys as they also include DLC. Meanwhile, the ongoing Android-supported Humble Bundle now offers 10 games, including Worms Reloaded, The Bard's Tale four others if you're willing to pay a little more than average.

Steam
86 Mass Effect 1 & 2 $9.99 (75% off)
74 Dead Island Franchise Pack $16.99 (66% off)
58 Dead Island Riptide $10.19 (66% off)
85 Euro Truck Simulator 2 $8.49 (66% off -- today only)
79 Mount & Blade: Warband $4.99 (75% off)  
82 Saints Row IV $33.49 (33% off)
57 Sniper: Ghost Warrior 2 $7.49 (75% off)
77 Killing Floor Bundle $7.49 (75% off)
83 Metro: Last Light $26.79 (33% off)
78 Spellforce Complete $12.49 (75% off)
83 AI War Collection $4.24 (75% off)
70 Sacred Collection $17.49 (50% off)
84  Eve Online $4.98 (75% off)
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Amazon Digital
84 Max Payne 3 Complete $9.99 (89% off)
88 The Walking Dead + 400 Days $7.49 (75% off)
72 The Cave $3.69 (75% off)
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GameStop
80 The Chronicles of Riddick: Assault on Dark Athena $4.99 (75% off)
85 Dark Souls: Prepare To Die Edition $7.49 (75% off)
71 Neverwinter Nights Diamond $4.99 (50% off)
80 D&D Ultimate Pack $22.49 (50% off)
88 F.E.A.R. Bundle $7.49 (75% off)
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GamersGate
79 R.U.S.E.: The Art of Deception Collection $4.00 
78 Dead Space 3 $10.20 (66% off)
89 Assassin's Creed 2 Deluxe Edition $5.99 (70% off)
75% off TrackMania titles
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GameFly
93 The Elder Scrolls V: Skyrim $14.99 (50% off)
78 Driver: San Francisco $6.80 (66% off)
67 Test Drive Unlimited 2 $6.99 (65% off)
90 Dragon Age Bundle $9.99 (80% off)
84 Max Payne Complete Package $14.99 (83% off)
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Green Man Gaming
92 BioShock Infinite $13.59 (66% off)
87 Borderlands 2 $10.19 (66% off)
Chivalry $8.49 (66% off)
75 Doom 3 $2.49 (75% off)
81 Brothers: The Tale of Two Sons $7.49 (50% off)
20% off select titles via "GMG20-50Z66-SCTEU"

Get Games
88 XCOM: Enemy Unknown $9.99 (75% off)
88 Tomb Raider $12.49 (75% off)
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GOG
60% off Rebellion titles