blarth: So long, and thanks for all the fish.
If you've read the books, you'll know the answer.
Cobi Treasure Deluxe RD7B5-KNMHR-YE..3
After The End: The Harvest B8VVF-IB..C-XVAAH
Dustforce DX 22EZE-J5VZW-CTK..
Once Bitten, Twice Dead! 94EV5-EBK33-..QGQ
Demon Hunter 2: New Chapter LBPC2-YAKZZ-7W..7
Bet On Soldier DIQNK-ENTZ5-..EJ5
ZombieRush FEYT2-5..ZA-RKINP
Disillusions Manga Horror DHB57-WYW8A-9..TY
Crowman & Wolfboy 3HCJW-..M00-NG9RR
Mythic Wonders: The Philosopher's Stone 9RGVF-KYF..-VZZM6
Millie 9IR7E-..84D-BATHV
Surfingers 2NFVC-6039E-..QVP
Surfingers 5CLGN-28..T-XLC45
Mechanic Escape 6TQJH-I..0P-0I98W
Coffin Dodgers F8KPZ-XHJZG-BFQ..
Gundemonium Recollection G886K-T9P5Y-..CLD
Belladonna ..2W3-E6487-5YD37
Ladra 3ZGVX-6E..R-CN2TV
NotGTAV D..PK-KGEED-VQ35H
Escape from Puzzlegate 9XVZ2-..H58-8EM35
The Silent Age ..Q07-E7CFJ-C6KP7
Pineview Drive 76H7K-XLY..-WVP0L
We Are Legion 8N43A-QRD8P-..GXG
All the keys are redeemed. For anyone who hasn't read the book, the answer is 42.