Coins

In Eugens Adventure
Coins are a currency found in Eugens Adventure while going through the levels, which you can collect to buy two characters: Eugenia and Justin, both cost 1000 Coins. Other than that, Coins are rather useless and just for being accumulated.

In Scrap Clicker
Coins here are literally useless, they're just used to be accumulated. They can be obtained through Minigames, on the Recycler, but it's still attracting to save up some coins... who knows for what.

Minigames
There are two minigames which can award coins.