Usually it's the other way around, but in a new update for the PS4 shooter Killzone: Shadow Fall developer Guerrilla Games has added a virtual currency called Valor, eliminating the need to use real money in the game.
Since launch players have been able to buy add-on packs containing various items such as weapons, skins or boosts for your character, to speed up the progression in the game's multiplayer mode.
You can still buy these pack with actual money if you like, but now you can also save up these Valor points earned inside the game.
The reasoning behind the decision is unknown, but it seems likely that this is done in an attempt to boost the game's popularity on the multiplayer stage. It might be too late though, with tough competition from heavy hitters like Call of Duty: Advanced Warfare now available.