the only dev that i know that managed to complete their project while working on another is siren's domainDevelopers working on multiple games concurrently is pretty much a death sentence, especially developers that are relatively new. Pirate King abandoned Dirty Pool, Eromersive abandoned Demon Boy and the other new game they were working on, Oseo Bones abandoned the Bones' Talkes games, etc. Even big devs that have completed multiple games seem to have a dip in quality once they start to work on multiple projects simultaneously, like Inceton.