http://steamspy.com/
Overall:
Total copies sold: 55,450,641
Average price: $5.46
Average discount: 55.61%
Steam ownership changes between 01.12.2015 and 01.01.2016:
Excluded titles: Batman games (free for Arkham Knight owners).
Steam ownership changes between 01.12.2015 and 01.01.2016 for games released in December:
Overall:
Total copies sold: 55,450,641
Average price: $5.46
Average discount: 55.61%
Steam ownership changes between 01.12.2015 and 01.01.2016:
Code:
1.) Counter-Strike: Global Offensive (858,927, LTD: 18,240,096, price $14.99, lowest price $$7.49)
2.) Garry's Mod (482,242, LTD: 10,579,546, price $9.99, lowest price $2.49)
3.) Fallout 4 (465,035, LTD: 2,735,251, price $59.99, lowest price $49.99)
4.) Rocket League (438,118, LTD: 2,226,942, price $19.99, lowest price $13.99)
5.) The Elder Scrolls V: Skyrim (423,270, LTD: 10,170,857, price $19.99, lowest price $4.99)
6.) Grand Theft Auto V (402,771, LTD: 3,832,550, price $59.99, lowest price $35.99
7.) Left 4 Dead 2 (397,417, LTD: 13,700,734, price $19.99, lowest price $3.99)
8.) Portal 2 (359,984, LTD: 7,686,377, price $19.99, lowest price $3.99)
9.) Insurgency (356,084, LTD: 2,453,732, price $14.99, lowest price $2.24)
10.) Undertale (349,620, LTD: 775,070, price $9.99, lowest price $7.99)
11.) Terraria (303,200, LTD: 7,074,266, price $9.99, lowest price $3.39)
12.) Star Wars: Knights of the Old Republic II (302,137, LTD: 1,701,169, price $9.99, lowest price $2.99)
13.) PAYDAY 2 (290,200, LTD: 5,756,942, price $19.99, lowest price $4.99)
14.) Life Is Strange (285,568, LTD: 948,852, price $4.99, lowest price $2.49)
15.) Star Wars - Battlefront II (284,900, LTD: 2,132,610, price $9.99, lowest price $2.99)
16.) ARK: Survival Evolved (272,828, LTD: 2,356,572, price $29.99, lowest price $17.99)
17.) Rust (265,886, LTD: 3,240,117, price $19.99, lowest price $9.99)
18.) Just Cause 3 (264,364, LTD: 387,043, price $59.99, lowest price $47.99)
19.) The Witcher 3: Wild Hunt (261,418, LTD: 1,265,914, price $59.99, lowest price $29.99)
20.) Just Cause 2 (259,824, LTD: 3,871,168, price $14.99, lowest price $2.24)
21.)Star Wars: Knights of the Old Republic (249,514, LTD: 2,159,545, price $9.99, lowest price $2.99
22.) Tom Clancy's Rainbow Six Siege (246,467, LTD: 246,467, price $59.99, lowest price $44.99)
23.) Chivalry: Medieval Warfare (233,281, LTD: 3,462,848, price $24.99, lowest price $2.49)
24.) Star Wars Jedi Knight: Jedi Academy (211,585, LTD: 1,320,767, price $9.99, lowest price $2.99)
25.) Counter-Strike: Condition Zero (206,873, LTD: 9,409,438, price $9.99, lowest price $4.99)
Excluded titles: Batman games (free for Arkham Knight owners).
Steam ownership changes between 01.12.2015 and 01.01.2016 for games released in December:
Code:
1) Hurtworld (187,679, price $24.99)
2) HELLDIVERS (105,775, price $19.99)
3) Squad (85,845, price $39.99)
4) RWBY: Grimm Eclipse (88,428, price $14.99)
5) LIGHTNING RETURNS: FINAL FANTASY® XIII (60,141, price $19.99)
6) Ghost in the Shell: Stand Alone Complex - First Assault Online (54,729, price $4.99)
7) Paradise Island - VR MMO (45,997, price $0.99)
8) The Mean Greens - Plastic Warfare (52,146, price $14.99)
9) Blood & Gold: Caribbean! (52,884, price: $19.99)
10) GUILTY GEAR Xrd -SIGN- (49,441, price $29.99)
11) Elite Dangerous: Horizons (45,013, price $59.99)
12) SimplePlanes (37,511, price $12.99)
13) Reveal The Deep (33,083, price $0.99)