To go the 100% enjoyable route, I need to know more things which naturally put people in this state. I do such things by experiencing them myself, and once they get there I know this is something which would fit in such a work.

Regarding this point, I think one of the most safe and efficient tricks to do this is to keep introducing novelty. If you have a game that has a fairly limited number of distinctive unique things that are introduced quickly and afterwards are simply repeated in different combinations it will less likely have such effect. For example a sandbox that introduces everything in 10h and then 90h you just play around with it will probably not have this effect, it can even become a chore. But a story-driven game which constantly introduces novelty on plot level but also sometimes introduces some new mechanics and content, have big chances to have this effect. In reality it’s more complicated, and there are many dimensions to this like challenge/frustration for example. There are games that use frustration as a tool to some extent to make winning certain fights feel exceptionally rewarding (soulslikes is the most popular example). But if you make it too challenging/frustrating there is a risk that player gives up and leaves in state of frustration which makes it a big failure. This particular thing is high-risk/reward type stuff.

Prey was very addictive to me. I think I beat it rather fast though, because I just couldn’t stop playing.