Must plays? That's a little gatekeeper-ey. At 40 years old all my "must plays" are going to be fairly inaccessible these days. I could hardly fault some random millennial gamer for never playing "Ultima 7" considering the computers it was designed to run on went obsolete before they were old enough to be able to use them. Or a game played on a cabinet, in an arcade, which are as easy to find as a pay phone these days. Or that they haven't really played online co-op until they have had to play Doom multiplayer by linking 2 ps1's together with a cable or having your computer dial your friends computer directly and tie up the phone lines at your house while you play. Those are the experiences that I consider necessary for somebody to be "a gamer." But I also acknowledge that those are kind of unreasonable standards and they say more about me than anyone else. Still, there are experiences that would be really powerful for someone to experience that I would recommend for any gamer. Things I found to be particularly impactful.
Wing Commander 3: This is a little unfair, as you would have had to play through 1, 2, and 2's expansion to get the most out of the reveal. But WC 3 reveals the identity of a traitor that destroyed the player's first carrier ship. A reveal I waited 4 years for. And turned out to be the ONLY COMRADE I ACTUALLY STILL TRUSTED. Still if you want it to carry the correct impact play Wing Commander, wait a year, play WC 2, wait 6 months, play WC 2's expansion missions, wait another 2 years, and then play Wing Commander 3. (see what I mean, unreasonable)
Silent Hill 2: I'm not alone in suggesting its a powerful experience. Its worth it.
Chrono Trigger: I actually prefered Cross, but Trigger is admittedly the classic. And actually FF 6 or even Secret of Mana work well for a "THE" this type of game.
Masters of Orion 2: THE classic for turn based strategy.
And, probably Ultima 7: Skyrim, a couple of decades before there was a Skyrim. Or Ultima 7: Skyrim, 4 years before Skyrim was even Daggerfall.
