Some games are great even if they are "done" and no longer under active development. Frostpunk is a good example. When you see it on a large discount, pick it up.

I have no problem at all with both methods (a "one and done" game/movie that will sell high for awhile and then go discounted, and a "work in progress" that continues to evolve over time and never discounts) - but it is very nice to know ahead of time.

Factorio did see a sale! I believe it was just on the Switch version though.

You can get a discount on humble bundle if you’re a subscriber