For the sake of adding something new, X is pareto optimal in terms of having both the best and the fewest games.
- Xenogears
- Xenosaga (maybe, haven’t played it yet)
- Xenoblade anything
- X-COM anything
I’d probably be content with only playing games from the Xeno- meta-series alone.
It’s quite easy, actually. I usually play everything years after release, however, if I’m really into a certain series, I’ll buy it right away. If I don’t care for the wait, I probably don’t care enough about whether or not a sequel is being made.
Of course that only works if you don’t get hyped easily. I play a lot of games, but usually only 1-2 per year are released within said year.