Hatoful Boyfriend (はーとふる彼氏/Hatofuru Kareshi) is an indie dating sim game where all the dates are pigeons. The game is available in both English and Japanese. The title is a pun on the words "heart" and "hato" meaning "pigeon/dove" in Japanese.
Despite its premise, the story of Hatoful Boyfriend is not just whimsical crack, there is an actual spoiler explanation of how pigeons came to be talking.
Hatoful Boyfriend is the best dating sim game I've ever played. There are 8 pigeons you can date every single one of them has a touching story (I know it sounds weird, but you get used to it). One ending was THAT sad, I started crying (or more than one, oh gawd). Let me explain what Hatoful Boyfriend makes that awesome!
As the fact that you can date pigeons isn't funny enough: every pigeon also has a human form (so you don't feel like dating pigeons, because you know what they look like as humans). And wow! They look pretty good ;)
As soon as you picked your favorite pigeon you start going to school (yeah, a pigeon school) and interact with your classmates and teachers. Your actions affect your love interest (if you do it wrong, it's even possible that your Senpai dies. :c), as in every other dating sim game.
You still don't believe the game is worth playing? Well, it SO worth playing, they even did 3 Drama CD's, an information book with background stories, a continuation of the game AND a manga (hatoful kareshi)! All these things are worth being played, heard and read! Because it's super funny and entertaining (and sometimes touching).