There’s this game called MIR4, a free-to-play MMORPG game where you can earn depending on your effort. This game can be played in both desktop and mobile and also supports crossplay. You need to mine around 100,000 darksteel to convert it in a coin called Draco that has a value of 0.3 USD as of December 20, 2021. Although the profit is not that much, it is still worth it for a free-to-play game.