It depends on what VN you're looking for. Which one do you want, I'll try find a Mac download link of it for you.
-----
Picked up
Isshuukan Friends.

It's actually pretty good. Hits you right in the feels. Reminds me of: Ef - a tale of memories.

well i am curious about Katawa Shoujou

http://www.katawa-shoujo.com/download.php

Download the full version. In MAC. If you have uTorrent or anything, I'd suggest downloading the torrent version but you can try the DDL version if you like. (there's no difference in the files, those are just download methods).

after i download it...how i run it?

Just install it like any normal game I guess.
-----
Finished Lilly route today, god damn that was so much better than Emi and Shizune's route. I feel so sad that it's over... I love Lilly's personality and how she acts, she's the best in that regard so far.

I'll do Hanako's route sometime next.

Couldn't get into Selector Infected, but No game no life is awesome so far though. Although there are quite a few animes I'm going to be enjoying the most, like:

Isshuukan Friends.
Sidonia no Kishi
The Irregular at Magic High School
Brynhildr in the Darkness
Bokura wa Minna Kawaisou

^ I have quite a few that I picked up:
http://www.anime-planet.com/users/Co...=eps&order=asc

Finished Hanako's route.

Was touching and had the feels at the end but I think overall I liked Lilly's the most. Hanako comes as a close second favourite.

I don't feel like doing Rin's arc, can someone "Spoiler" that happens in her route, what is her issue and does she always not make sense?

It'll a blast i am sure of it