NetHack is quite a popular roguelike game, created in 1987 but the current version was released in 2003.
The game is a hack n slash kind of game but has a subtle humor and intellectual elements making it more popular with mathematicians, programmers, engineers and the like.
As @SLC mentioned; you can watch people playing it or play it yourself in real time using telnet or a browser version at alt.org/nethack
Best Answer
It appears to be a game called 몬스터슈퍼리그 (translit: monseuteosyupeoligeu), which translates as Monster Super League.
Here are the links:
Play Store
App Store