Japanese Title: 幻想LIAR GAME
Artist: shino_(ponjiyuusu)
Artist's pixiv: Here

A game about who is the best liar in all of Gensokyo.
Series by 4 Eps. sold exclusively at Comikets(C77-C78-C79-C80) -> Episode 1 I "the current one (Comiket 77/C77) -> Episode 2 was sold at Comiket 78(C78)-> Episode 3 III pool #6305 (Comiket 79/C79) -> Episode 4 IV (FINALE) was sold at Comiket 80(C80).