Star Wars: Squadrons
This game was infuriating for the enormous wasted potential that it was. From the day of launch they said they were planning to never update it, add to it, or expand it.
It could have been the successor to X-Wing/TIE Fighter, but they starved it from the beginning. The multiplayer was bad and they only had a few servers in the US, so it was too laggy for everyone overseas.
The game could have been something great, but it was dead out the door.