All the big juggernaut PC titles are all clones of PC games and further developed solutions but based around the same concepts. ( Dota's / BR's / overwatch etc.
To give you a idea what the mod is about it was hugely populaire on counterstrike servers.
U could choose different classes like orcs or humans elf etc and everybody had there own thing. U had skill choices like throw big nuke nades, had a ult that if you die u explode. When humans could teleport and go invisible. U choose when u get x amount of experience on what you get or what class u got.
I would sit invisible in weirdest corners death still in the hope somebody wouldn't see me and i could kill a bunch of people. Loads of fun.
U could experience up etc, it was hugely fun to play and well done.
Mods for warcraft 3 and half life and quake where way in front of there times. There where huge mods that where insanely massively like huge BR maps of entire city's where people would fight loot and get stuff etc before br where a thing. They where all free also because they where mods even counterstrike was completely free and had its own mods.
U had pokemon world where u had a entire map, where you could with a ton of people catch pokemons, level them up and do a tournament fight after it.
Where u where defending one group against the other group the gates of lord of the ring of that castle which was massive hype.
U had entire mods like dragonball z fighter in huge maps with loads of people together, where u could transform level up, do beam fight struggles, combo attack eachother with 20 other people on the same map. Where u could collect dragonballs and summon dragon to get whatever u want as reward, which resulted in a huge brawl when somebody almost had it collected etc.