At first I ony played completed games. But now I'm also exploring ongoing games, but only if the update cycle is somewhat frequent and content rich. It shouldn't take a year to update a single scene...
Sandbox = It HAS to be a dev with a great track record with completing games. I'm NOT ever again playing a Sandbox and oops, "Start a new game" or "Abandoned." AVN = I'll do an ongoing game IF it has my tags. I'll wait a bit though. Exception: On Release 1, again, ONLY if it's a dev I like.
By playing only completed games I would have skipped "But I'm the bad guy" which (I think) would be a miss. So I'm glad I play everything I think would be fun.
if its an ongoing game i make sure to check if theres a satisfying amount of content. for renpy games at least i make sure theres at least a 2 gb download before i try it