Have: >500 games on various platforms (Steam, GamersGate, Desura, GOG, ShinyLoot).
Check my list. Please note that the document has 4 tabs: One ordered by game title, one ordered by platform (useful if you're only interested in games for a given platform like Steam or Desura), one with explanations about keys and platforms, and one with general information for traders. You can change tabs with the buttons in the bottom row.
Want: I will generally trade any game in my list for any Steam or GOG game of similar value that I don't have already on that platform.
My Steam profile is public, so you can easily check which games I already have. I am only interested in legitimately obtained keys from reputable stores.
Previously traded with / gifted games to: Quite a few people, but it's been a while ... recently traded games with Grargar, Heretic777, Cmdr_Flashheart, alexkoti, chean, BranjoHello, samlii, koima57, undeadcow, DarkoD13, Giltonnam, Rexoberan, Badseeder, Leroux, The.Kuribo, Fluent2332, Tokisto, Innerring, mchack, siulebuo, v3, Catshade, Grargar, and hummer010, as well as cards with JMich, samlii and Rodzaju.