Fallout 2 isn't as refined and tight as Fallout but I personally enjoy it more. It's arguably far too big but as I've played it so many times (unusual for me - I'm usually a one-and-done person when it comes to time sink RPGs) that isn't a bad thing. I enjoy the writing, mechanics, and atmosphere. Also I voice a robot dog in a mod for it.
Red Alert 2 is the best C&C game ever. I do not care for any of the 3D ones and Red Alert 1 is rather too difficult for me. However RA2 I have finished on hardest difficulty several times. I've never really bothered with the multiplayer for it outside of co-op because I don't play to be competitive. I tend to take my time and like it that way.
Broken Sword: The Shadow of the Templars is maybe my favourite point and click RPG. I go back to it every few years and it always sucks me in. I know most of the puzzles off by heart but I'm more there for the sense of escapism and gentle humour. There's other amazing point and click games but for whatever reason this one really speaks to me. It's not even a nostalgia thing - I've only ever played the 2009 director's cut! I'm old enough to have played the '90s version but never did.
Honourable mentions:
*Startopia
*The Binding of Isaac: Rebirth
*Theme Hospital
*What Remains of Edith Finch
Startopia's music, humour, and gameplay are all top notch. Runs on a potato, makes me laugh, and features my old pal, Arona.
BoI:R is great. I've put a ridiculous number of hours into it. The latest DLC has made it a bit too big for my tastes but in general I enjoy it a great deal.
Theme Hospital is like Two Point Hospital but tighter, funnier, and prettier. Lots of fun.
What Remains of Edith Finch is art. It's funny, moving, tragic, and beautiful. I encourage everyone to play through it. It won't take that long - a few hours. Such a fantastic experience. Gone Home is pretty damn good too.
Red Dead Redemption's Undead Nightmare was excellent.
I quite like most of the The Binding of Isaac DLC (although sometimes they're a bit too big, to be honest).
The Vietnam DLC for Battlefield: Bad Company 2 was also rather good. I didn't get to play as much of it as I might have liked but I remember it being more than just a resin.
Bonus: Red Alert 2: Yuri's Revenge (an expansion pack rather than DLC admittedly)