Deploy to the caverns under a Mars terraforming station where you discover it's just a front for another sort of operation: the sort with designs for regional conquest! Your choices during your infiltration result in RP, the currency for unlocking several different tower defense buildings for the endgame.

https://querius.itch.io/mars-bioengineers

In order to survive, your choice of three commander characters must learn to dodge globs of acid spit and the deadly mandibles of war roaches, take down some mutant horrors freshly escaped from their labs, and think up an optimal configuration for your base buildings, a base which can be attacked from multiple sides.

The trailer:  Mars Bioengineers trailer