They don't allow end-users to generate keys for games - that is restricted to the publishers or game creators (in smaller cases). The keys on those sites are g

They don't allow end-users to generate keys for games - that is restricted to the publishers or game creators (in smaller cases). The keys on those sites are generally sourced from physical copies in cheaper regions (as mentioned in a sibling comment), cheaply sold bundles (Humble Indie Bundle, and other similar sites), and other such sources. You could possibly make an argument for gift-copies of games[0] being resalable, or games that can be added to third party systems (ME2 gives a CD key that can be added to Origin, for example) though the latter would be limited to one attempt per-game per-account. [0]http://www.g2play.net/category/24773/factorio-steam-gift/ http://www.g2play.net/category/24773/factorio-steam-gift/