Octodad

"Fatherhood can be difficult. Especially when that father is an octopus."

Octodad is a freeware game by a team of students from DePaul University. To quote the official site, Octodad is a third-person adventure game about destruction, deception and fatherhood. The player controls Octodad, a dapper octopus masquerading as a human, as he goes about a day of his life. His existence is a constant struggle, as he must master mundane tasks with his unwieldy boneless tentacles while simultaneously keeping his cephalopodian nature a secret from his human family.

You can read about and download the game here. Octodad returned in Octodad: Dadliest Catch in 2013, when he must deal with his increasing suspicions of his wife and his own watery past during a trip to the local aquarium.

Tropes used in Octodad include:

Art Shift: Cutscenes are in a moving comic format, alternating between a Animesque style and a more traditional style.
Cardboard Pal: Octodad's main objective is building a fake self so that he can buy himself some time to make an anniversary gift for his wife. It ends up saving his life.
I Thought It Meant: A lot of people didn't entirely realize why Octodad needed a banana for the disguise, until he assembles the decoy. It's to mimic his mustache.
Evil Chef: Fujimoto might be right about Octodad, but he doesn't have to be such a Jerkass about it in the final part.
Good Dad: He may be an octopus, but he's still a pretty good dad for making sure his little girl Stacy gets a good night's sleep free of monsters and spiders.
Human Mom, Nonhuman Dad: He IS Octodad, after all!
Last-Note Nightmare: Screwing up too much and raising your Suspicion meter will cause the music to go increasingly off key.
Let's Get Dangerous: "GAME FACE"
Let's Play: A very funny playthrough by the Freelance Astronauts.
Little Miss Badass: Little Miss AND Little Mister due to Stacy and Tommy who become pretty damn brave at the end in saving their father from the evil psychopathic chef, by throwing their toys at him.

Stacy: I don't like your hat!

Naughty Tentacles: Oh so very implied.

Wife: Oh I can picture every detail... I was stowed away on that fishing boat and...

Paper-Thin Disguise: The furthest it goes is arranging his tentacles into a vaguely humanoid shape and putting on a suit. Only one other man notices, and he's written off as crazy. Not to say he isn't.
- "I AM WALKING LIKE THE NORMAL MAN-PEOPLES!"
Say My Name: OCTODAAAAD!!
Standard Fifties Father: Octodad tries to be one.
Stranger in a Familiar Land: Implied by the end of the sequel's teaser trailer.
The Unintelligible: Though quite eloquent in his journal entries, Octodad's dialogue is simple blubbering. His points get across quite well, though.
Unmoving Pattern: In the kitchen cutscenes.
Wreaking Havok: Part of the fun to the game is just tossing stuff around and stumbling about.

Nobody suspects a thing...