I think in general I tend to ask myself these questions:
can I role play as someone else?
is there a branching storyline that can be replayed in different ways?
is there an open world with tons of nooks and crannies to explore?
can I dress up? :)
is there a fun and novel gameplay mechanic?
Usually I’m invested if it ticks several boxes. I love long, story heavy rpg’s like BG3. But also visual novels like Roadwarden, open world like Shadow of Doubt, or more experimental like Book of Travels.