After that, Wwe played Mahjong and a video game.

Mahjong is a Chinese game, played forby three or four people.

People often play it as afor gambling bettingand bet money, even which is illegal in Japan.

(Of course, we didn't do that.) It is often said that college students who play Mahjong tend to fail their tests and go astray.

However, Mahjong is exciting.

This is correct, but it sounds a little blunt, (a strange conclusion). もう少し、意見を説明するのが必要だと思います。"But, I can understand that (麻雀をするために徹夜すること), because Mahjong is so exciting."とか、なんでもいい。

After that, Wwe played Mahjong and a video game.

Mahjong is a Chinese game, played forwith three or four people.

People often play it as ato gambling bettinge and bet money, even which is illegal in Japan.

"betting money" is redundant because gambling implies that. But you could use both phrases to emphasize the action.

(Of course, we didn't do that.) It is often said that college students who play Mahjong tend to fail their tests and go astray.

"go astray" sounds formal, but I still understand what you mean.

This is because Mahjong needs a certain number of people, and once a game starts, it takes so much time that people often stay up all night.