The Bard's Tale - Hilarious, and I am a sucker for anything that involves summoning a squad to fight for me.
Psychonauts - Absolutely delightful. Just cute, funny, weird and imaginative. The platforming itself is good, though it gets really hard towards the end.
Eternal Darkness - By far my favorite horror game. None of the terrible controls, bad cameras, or bullet sponge enemies beating you with a wet noodle to give the impression of danger. Just a lovecraftian horror story full of great atmosphere and character, with the twist that as your character's sanity meter goes down, shit gets weird, and sometimes breaks the fourth wall.
Skies of Arcadia - I cannot stress enough just how much I love this game. Sky pirates flying between floating islands in endless sky during an age of adventure and exploration.
The Zelda Series - The original is still worth playing, but you'll want to look up the map that it came with. A link to the past is beloved, but Link's Awakening is the real nostalgic one for me (I have the switch remake and haven't had a chance to try it yet). I still think Ocarina of Time holds up, but I understand that many disagree. Majora's Mask is great in many ways, but it is a game that works best when you have a lot of time to explore and discover things on your own, and as a grown ass adult with a Job and responsibilities, I had trouble going back to it and not just looking stuff up in a guide, which diminishes things... I also don't have time to list my thoughts on the entire series.
KOTOR 1 & 2 - Pretty much what I wish every new iteration of Star Wars would aspire to be. The second one is a bit more uneven, as it had a vision that was truly inspired, but was forced out on an extremely rushed time frame, so a lot of things got cut, and even the restoration mods can't add everything back in. (Also, Dragon Age Origins, as long as we're talking classic Bioware)
Star Wars Republic Commando - A great FPS with a squad that actually knows how to do their jobs, and which does a good job of showing the clone wars from the perspective of a soldier. (Honorable mention to Jedi Outcast and Jedi Academy which are still the best Jedi based action games but which had some technical issues the last time I tried to play them)
Castlevania Circle of the Moon - Everyone talks about Symphony of the Night, and I won't argue with them, but my all time favorite in the series has to be Circle of the Moon. Refined Castelvania gameplay with a unique magic system that is simple but satisfying.
Punchout (with or without Mike Tyson) - The original is a classic and it holds up surprisingly well.
Halo 1, 2, 3 ODST, and Reach - They each hold up in their own unique way. The first one is immersive and is extremely well polished mechanically. The second has a stronger story and adds the bonus of being able to swap weapons with teammates (give them the scoped weapons, keep them alive, live or die as a unit), the third has awesome mechanics but weaker storytelling, ODST is Halo 3 Band of Brothers Edition, and Halo Reach actually tells the best story while taking the gameplay back to its roots.
Cursed Halo - It's Halo 1, but completely insane. It manages to actually be fun while also being completely ridiculous.