I had a friend of mine who was playing alot of Dota2 using literally a calculator.
You can google, there are many ways to run games on super weak hardware (you will pay with quality of graphics, but still)

Dota2 is a MOBA, where you play 5v5 trying to bust enemies ancient (throne), pretty much warcraft-ish kind of experience (WCIII, not WOW)

Also yes, warcraft III also will do the job and there are alot of custom games inside the game itself