A for Atari
B for Bungie
C for Colecovision
D for DICE
E for EA
F for Funcom
G for Gameloft
H for -----------Please help!!!
I for id software
J for again help needed !!!
K for konami
L for Lucas Arts
M for Microsoft Game Studios
N for Nintendo
O - Dont Know
P For PopCap Games
Q - nobody keeps a company name that starts with 'Q'...hmm..... may be i should start one.
R for Rockstar Games
S for Sega
T for THQ
U for Unreal Engine
V for Valve Corporation
W for Warner Bros Interactive
X for Xbox 360
Y for YOYO Games
Z for Zynga

if you can recall any games which these developers have developed mention them in comments below.......hey you there don't google it!!!

also one more thing , Help me with the missing letters and your efforts will be rewarded