Games like Obviously Inappropriate Content
Games like Obviously Inappropriate Content include Undertale, To the Moon, OneShot, Do Not Feed the Monkeys, and Impostor Factory. We matched them by the tags players give Obviously Inappropriate Content on Steam (Political Sim, 2D, Pixel Graphics, Dark Humor, and Fantasy): closest matches first, and among equally close ones the better-known games.

Undertale
Shared: Pixel Graphics · Choices Matter · 2D

To the Moon
Shared: Pixel Graphics · Interactive Fiction · 2D

OneShot
Shared: Pixel Graphics · Cute · 2D

Do Not Feed the Monkeys
Shared: Political Sim · Dark Humor · 2D

Impostor Factory
Shared: Pixel Graphics · 2D · Adventure

Finding Paradise
Shared: Pixel Graphics · 2D · Interactive Fiction

Vampire Survivors
Shared: Pixel Graphics · 2D · Casual

DAVE THE DIVER
Shared: Pixel Graphics · Casual · Adventure

Reventure
Shared: Pixel Graphics · 2D · Dark Humor

The Cosmic Wheel Sisterhood
Shared: Pixel Graphics · Interactive Fiction · Choices Matter

Graveyard Keeper
Shared: Pixel Graphics · Dark Humor · RPG

Shovel Knight: Treasure Trove
Shared: Pixel Graphics · 2D · Retro

LISA: The Painful
Shared: Dark Humor · Pixel Graphics · Choices Matter

DELTARUNE
Shared: Pixel Graphics · 2D · Fantasy

Sonic Mania
Shared: 2D · Pixel Graphics · Retro

A Bird Story
Shared: Pixel Graphics · 2D · Interactive Fiction

Melvor Idle
Shared: Casual · 2D · RPG

Storyteller
Shared: 2D · Interactive Fiction · Fantasy

Kingdom Rush Frontiers - Tower Defense
Shared: 2D · Fantasy · Choices Matter

There Is No Game: Wrong Dimension
Shared: Pixel Graphics · Casual · 2D

NEEDY STREAMER OVERLOAD
Shared: Pixel Graphics · 2D · Dark Humor

Until Then
Shared: Pixel Graphics · 2D · Interactive Fiction

UFO 50
Shared: Pixel Graphics · 2D · Retro