Hi

Me and some of my friends in spare time wrote (again) a game (indie, crazy carts racing with guns and chainsaw ;).

Now when the game is almost finished from the code point of view (more tracks and cars need to be modelled and added)

I need to add some leaderboard/achievements/micro-transactions system to it. We have our in-engine local achievemnts/leaderboards tables but from the marketing point of view it will be a lot better to have global ones.

Game will be free - with micro-transactions system (to buy updates, unlock new levels, etc. (but balanced not to be pay-for-win))

Game is writen on our own enigine - (mainly c++ with objective-c/java mixup for iOS/Android) - supported platforms are: Android (2.3 and up), iOS, LINUX and WINDOWS

So here I have a real question:

Is there any micro-transaction system that supports ALL of those platforms ?

(on our previous projects we'v used scoreLoop but it is only Android/iOS), same with google play services.

I'm doomed to use Steam on Win/Linux and scoreLoop on Android/iOS or is there any 'magic' platform that spans accors all 4 ?

I'v came accross facebook Game services - it's seems to be platform independent - and support what I need

Any other popular solutions ?