Relief. Pride. Exhaustion. "Thank god it's done". All these feelings and more. Like sending a child out into the world for the first time. Scary.
Of course not all games take a long time to develop. Not all developers have such a high level of emotional investment. Not all of the games do well. But there's something incredibly gratifying about spending lots of time, thought, effort, and, yes, love, on a project and when it's done seeing it out in the world. People playing it : people you've never met and will never meet gaining some pleasure from tramping through the levels you spent so much time tweaking and testing. Reviewers casting an objective and critical eye over something you ceased to be objective about so very long ago. The feeling of surprise and exploration they experience when they discover things you had written down on files and scraps of paper and spent all those hours implementing.
What you would give to be able to remove all memory of your own game and to be able to sit down to it and look at it with fresh eyes.
But you will never feel that way about your own game.
Because you're the one that made it all happen.
I think that everyday! When I first started working on my current project it was and still is a passion project. A game I would love playing when it was done. The problem is the closer I get to completion the sadder I get because I can't sit down and enjoy it like others. I will spot every flaw, understand every imbalance and never really be immersed like I hope others will. It's a double edged sword this game development!