IMHO, leekwars is not similar. Leewars, like robotcode, is one game with one language.
codingame is a set of puzzles (solo), mutli-player/challenges, periodic contest, clash of code (race of coding)… Where you can use the language like (except for some puzzle). It’s also a good place to see advantages and disadvantages of languages vs others for some context.
I used the site to learn Rust, and it was more funny than with puzzle from project euler or C-99.
On puzzle you can also compare your solution to others and learn a lot.