From Citizen Sleeper Wiki

Cryo is the main source of currency within Citizen Sleeper. It can be collected by players and used to complete missions and, therefore, advance their clocks and level up. Each mission that a player completes cost a differing amount of cryo, therefore players must chose wisely what they wish to spend their cryo on.

Cryo can be obtained by players through the completion of tasks throughout the Eye with their dice. For example, players may obtain cryo through the completion of salvage repairs on the Eye or hull dissection. The amount of cryo earned by each task completed depends on the difficulty level of the task; tasks marked as safe are almost always guaranteed to generate a profit for players.