Level Stacking (2018) was a game jam entry in the 5 city Game Jam hosted by Arctic Game Lab, built in Unity. Although it’s not one of the submissions, it was a short prototype I made alongside helping other participants.
The mechanic allows the player to “claim” land on one level, and having that land act as a safezone when descending to the next level. Each claimed tile requires upkeep, so the more land the player claim, the more resources they need to gather to maintain control of that land.