These titles can be redeemable on Steam.
Some titles in GamersGate and GMG will usually warn you if they're Steam-only on their description. If they're not on that list they're more than likely not work on Steam.
Comment has been collapsed.
Actually, these two posts:
GamersGate games that can be activated on Steam
GMG games that can be activated on Steam
Are better sources. The official Steam article lists games whose keys have to match specific formats - some of those games on GG/GMG have different formats that won't activate on Steam (e.g., Mount & Blade keys from GMG don't work in Steam - source: experience).
Comment has been collapsed.
163 Comments - Last post 30 minutes ago by Reidor
12 Comments - Last post 41 minutes ago by Tourfaint
157 Comments - Last post 1 hour ago by SkeetSurfer
418 Comments - Last post 2 hours ago by Nikitanz
13 Comments - Last post 3 hours ago by ViTALiTY
12 Comments - Last post 4 hours ago by Lugum
14 Comments - Last post 5 hours ago by kampeao
511 Comments - Last post 23 minutes ago by Tucs
3 Comments - Last post 27 minutes ago by Zynthet
258 Comments - Last post 31 minutes ago by Lugum
0 Comments - Created 32 minutes ago by Lugum
0 Comments - Created 40 minutes ago by Lugum
1,526 Comments - Last post 1 hour ago by kornobi
118 Comments - Last post 2 hours ago by Alpha2749
Are games bought on GamersGate and Green Man Gaming redeemable on Steam?
Comment has been collapsed.