So far it's squad tactics. More like Fallout Tactics than Fallout 2.
And Gorky 17 is more like chess.

"Wandering around" more like "Arkanum" and "The Fall".

No mutants Allowed has everything you want to know, also hi-res patches: http://nma-fallout.com/

The most popular unofficial mod/update to F1 is "Fallout Fixt", and the aforementioned, Restoration Project for F2. They both adds quite a lot and are still active. http://www.nma-fallout.com/forumdisplay.php?18-Fallout-General-Modding

a bit; mashed

I think what I find most intriguing about Fallout is the choices you make and the freedom of playstyle you get. There are so many ways to progress, from talking it out wittily to blowing up everything. And I always felt the dialogue to be very interesting. In that way I would compare it to Deus Ex. While it is more of an FPS, it has great choices that really vary gameplay. Of course no traditional RPG open world exploring and combat.

I think <span class="bold">Crimea</span> hasn't been mentioned yet.

Your right I didn't like it much in the sense to a RPG but a story and an atmosphere its nice feel. Its a one time play game. Enjoy the moment and move on. :) I too prefer true RPG games but they're lacking these days.

Neo Scavenger.
Arcanum.
Geneforge games.
Arcanum.
Arcanum.

Since it is a topic that I am also interested in, I have compiled and summed up all the answers so far.
In my opinion, I believe that you should just mod Fallout 2 with a fresh mod and enjoy a different recreation of the game.
Because Fallout 2 is too unique of a game.

Sorry mate but Arcanum gets only a single vote from you, even though I can see you are pretty excited to recommend this game :D

Here we go:

Arcanum - 7
Underrail - 4
Fallout 2 - 3
Pillars of Eternity - 2
Fallout New Vegas - 2
The Fall - The Last Days of Gaia - 2
Borderlands - 2
Wasteland 2 - 2
Gorky 17 - 2
S.T.A.L.K.E.R - 2
Fallen - 2
Geneforge - 2
Neo Scavenger - 2
The Age of Decadence - 1
Shadowrun: Dragonfall - 1
Divinity - 1
Diablo - 1
Ultima 7 - 1
Baldurs Gate - 1
Prince of qin - 1
Fallout 3 - 1
Don't Starve - 1
Metro - 1
Planet Alcatraz - 1
Elder scrolls - 1
After Reset - 1
Fallout Tactics - 1
Deus Ex - 1
Crimea - 1

No planescape torment?
The combat system is completely different, but its from the same company (Black Isle), and it has a similar emphasis on dialogue.
In fact it revolves a lot around dialogue; its one of the most lore-heavy and the most text heavy game I have played

Try gameslikefallout.com there is list of 15+ Fallout like games

there is a very old game called fallout

Fallout 1.5: Resurrection is a total conversion mod that is very good- a brand new large story.