RPGaDay, day 20

Day 20: Will still play in 20 years time…

Call of Cthulhu and Dungeons and Dragons are classics that are flexible enough to keep them fresh, even if I end up drifting from the default settings. I can't imagine not wanting to play either of them. I think the thing is, they're simultaneously specific and generic. You can run one of the actual D&D worlds, or you can use the same ruleset to run a massive variety of fantasy games with different tones, themes and content - even the magic system and metaphysics have alternative rules and are hackable. Exactly which edition would be a subject of, ahem, debate amongst my friends. Call of Cthulhu is again usable with any sort of vaguely weird fiction, and can be set in the past, future or an alt-hist if you prefer with only minimal tweaking. Neither has any very specific rules that the game is built around, so they're forgiving of tinkering, but even so they have their own distinct flavour in the default.

I'd also lay good money on Deathwatch because of my abiding love for the universe, although Games Workshop may have perished and/or decanonised all that I hold dear by that point.