Antimatter

Antimatter is a type in-game currency. Antimatter is used to purchase certain buildings and upgrades, purchase and rent certain troops, as well as being the exclusive type of currency used to build and upgrade the space base. Antimatter can also buy extra weapons, titanium mines, energy generators, mercanairies, and other useful items for your regular base. Antimatter can be obtained by raiding space bases, reaching certain milestones during the limited operations, participating in tournament leagues, wars, raids, duels, and by converting energy and titanium in the space base via the ETA(Energy to Antimatter) Antimatter Generator and the TTA(Titanium to Antimatter) Antimatter Generator.

You can spend green crystals to buy antimatter, but take into account that 200 antimatter costs 200 crystals, but 1000 antimatter costs 866 green crystals.