Stardust is an in-game token that you can earn while playing.

• Explorations
• Burn planet
• Season Rewards
• Shop (Linking to purchases in the shop will be tuned off on Nov 24, 2019 20:00:00 UTC)

"What means Total Supply: 25,270,222.497 Stardust? Is this the maximum possible amount of stardust?"

Total supply ist not max. supply.