Games like Decline's Drops
Games like Decline's Drops include Celeste, Internet Generation, Super Meat Boy, SANABI, and RWBY: Grimm Eclipse. We matched them by the tags players give Decline's Drops on Steam (2D Platformer, Beat 'em up, Precision Platformer, Spectacle fighter, and Collectathon): closest matches first, and among equally close ones the better-known games.

Celeste
Shared: Precision Platformer · 2D Platformer · Platformer

Internet Generation
Shared: 2D Platformer · Spectacle fighter · Beat 'em up

Super Meat Boy
Shared: Precision Platformer · 2D Platformer · Platformer

SANABI
Shared: 2D Platformer · Action · Platformer

RWBY: Grimm Eclipse
Shared: Beat 'em up · Spectacle fighter · Action-Adventure

Stick It to the Stickman
Shared: Beat 'em up · 2D Fighter · Action

Momodora: Reverie Under The Moonlight
Shared: 2D Platformer · Spectacle fighter · Female Protagonist

Anomaly Agent
Shared: 2D Platformer · Platformer · 2D Fighter

Mina the Hollower
Shared: 2D Platformer · Action-Adventure · Platformer

Webbed
Shared: 2D Platformer · Platformer · Cute

VVVVVV
Shared: Precision Platformer · 2D Platformer · Platformer

Brawlhalla
Shared: 2D Platformer · 2D Fighter · Platformer

Bō: Path of the Teal Lotus
Shared: Precision Platformer · 2D Platformer · Platformer

Rusted Moss
Shared: 2D Platformer · Platformer · Precision Platformer

A Hat in Time
Shared: Collectathon · Platformer · Female Protagonist

Pizza Tower
Shared: 2D Platformer · Platformer · Indie

Downwell
Shared: Precision Platformer · 2D Platformer · Platformer

Tribal Hunter
Shared: 2D Platformer · Beat 'em up · Platformer

Castlevania: Belmont's Curse
Shared: 2D Platformer · Platformer · Female Protagonist

Katana ZERO
Shared: 2D Platformer · Platformer · Action

BlazBlue Entropy Effect
Shared: Platformer · Action-Adventure · 2D

Guacamelee! Super Turbo Championship Edition
Shared: Beat 'em up · Platformer · 2D

Planet of Lana
Shared: 2D Platformer · Female Protagonist · Platformer

Afterimage
Shared: 2D Platformer · Female Protagonist · Platformer