Meaning of “ReseMara(リセマラ)”

“ReseMara(リセマラ)” is an abstraction for “Reset Marathon (リセットマラソン)” which means resetting a video game repeatedly in order to get a good charactor or parameter or so. Doing it takes long time and may not be achieved. It’s a long shot, but many people try it to get good something on video games.
This is a slang among gamers.

Example Conversation

A: Oh, again! failed!
B: What are you doing?
A: I repeat resetting this game to get my oshi(推し)
B: ReseMara(リセマラ)… it must be tough.

A: あー、まただめだった。
B: 何してるの？
A: 推しキャラゲットするためにリセットしまくってる
B: リセマラか…大変そうだね