This game is from the same developer that brought us Turf Wars. Turf Wars is a great game that I personally have played for over 3 years. Global Supremacy is similar to Turf Wars in many ways. It is a free multiplayer game about amassing territory and power. It uses GPS to acquire territory and has the ability to form "alliances" to build up power through numbers.
However GS differs from TW's in two very key areas:
First, no code entry necessary! In TW's you need to enter in invite codes of other players to "grow" your mob size. GS still has mob (called agents) to grow but you gain them as loot items while doing missions.
Second, no airports! In TW's you are granted an airplane ticket every two weeks that you can use to travel (in game) to pretty much every major airport that exists in real life. Originally there were no airports in TW's and if you wanted turf somewhere you didn't live, you had to literally travel there in real life. Then airports were added and now you have access to wherever you like. This allowed players that had spent large amounts of real money on the game to exert their power over virtually everyone in TW's. GS is location based without airports and I prefer the smaller scale.
I recommend this game and if you try it and have any questions please message me in game and I will gladly answer all questions. My in game name is Arboc Suomonev (Venomous Cobra).