It is yet another different iteration of 2d20 so the least played in my circle, but I got it because the CRPG was another of my childhood classis, though this TTRPG is mpre based on Fallout New Vegas.
The computer game influence probably convinced Modiphus to increase the Attributes to spell "S.P.E.C.I.A.L" and also include multi-damage track, like physical and radiation. , Abd hit locations are back here too, because you know, CRPG-inspired armour needs to prove its use.
In summary, despite being published in tandem with Achtung Cthulhu, the Fallout RPG did not use the 2d20 SRD as purely as Achtung Cthulhu does. .
Overall, Fallout sits in a halfway house between Conan and Star Trek.
The rules are more broken in this halfway house, sadly.
If you like the computer game, Fallout, this RPG is worth it. I only got the core rules myself. Though more books are now available including "Winter of the atom" campaign
You will not notice the broken rules much. It is because being halfway between Conan and Star Trek, balancing Momentum is a challenge, but an experienced 2d20 GM can easily fix that. Also to simulate the weapons and armour in the CRPG, Modiphius added more rules gimmicks.