Games like Fission Simulator
Fission Simulator. These games share the most with it, and each one says why.

Fundamental
Also physics, pure numbers
Start with a single particle and build up the universe. Galaxy's most-played game by total hours, by a lot.
4.4★ galaxy65% idle
Incremental Mass RewrittenDormant
Also pure numbers, physics
Gain mass, become a black hole, then an atom, then a supernova. The numbers get absurd quickly and never stop.
4.4★ galaxy60% idle
Distance Incremental
Also pure numbers, physics
Go faster, go further. Rockets, time reversal and a very long list of layers from the Prestige Tree author.
4.4★ galaxy55% idle
Universal Reconstruction
Also science, physics
Stranded in a void with one skyrmion, you gather and combine components to rebuild reality. A Profectus remake inspired by Distance Incremental.
3.9★ galaxy
Idle Research
Also science, pure numbers
Research and craft flasks and tubes to generate three kinds of energy, with several prestige types, fights, skills and potion brewing.
85% steam50% idle
Particle ClickerDormant
Also science, physics
Run a physics lab and work through the history of high energy particle physics by clicking to collect data.
Incremental Mass: Classic ReloadedDormant
Also pure numbers, physics
A reloaded version of the classic Incremental Mass, where you grow your mass through layered resets.

Infinite EaterDormant
Also pure numbers, physics
Eat things smaller than you to grow and eat bigger things, in an incremental take on agar.io and Tasty Planet.

Antimatter DimensionsUpdated
Also pure numbers
Buy dimensions that buy dimensions, then break infinity, then break reality. The reference point every numbers-go-up game is measured against, and it has a real ending.
92% steam4.6★ galaxy200–600h ending55% idle
DodecaDragons
Also pure numbers
Twelve dragons, twelve colours of magic, and one of Galaxy's most-favourited games. Big numbers, handsome UI.
4.6★ galaxyhas ending55% idle
Calculator Evolution
Also pure numbers
Upgrade a pocket calculator into something with far too many digits. Clever programming-flavoured progression.
4.5★ galaxy55% idle
The Prestige TreeComplete
Also pure numbers
A skill tree where every node is a prestige layer. It spawned the Modding Tree and a thousand descendants.
4.6★ galaxy30–80h ending50% idle
Algebraic Progression
Also pure numbers
Grow variables, unlock functions, climb the algebra. A math incremental with a following.
4.4★ galaxy
Black Hole FishingUpdated
Also science
Use a black hole to vacuum fish from a pond, then breed, inject traits into and research them while feeding the singularity to grow it.
89% steam
Ordinal Pringles
Also pure numbers
A spiritual successor to Ordinal Markup: climb the ordinal hierarchy, one absurd notation at a time.
4.4★ galaxy45% idle
Idle Gumball MachineUpdated
Also physics
Fire gumballs into spinning gears in a plinko-style board, buy upgrades for explosive number growth, and ascend to trade everything for stronger bonuses.
91% steam25% idle
Berry Bury Berry
Also physics
Grow berries in a first-person garden and drop them into a strange hole for cash, upgrading helpers while an unsettling mystery with several endings unfolds.
98% steamhas ending
Version Control
Also pure numbers
An Antimatter Dimensions-style game made for a jam where you move through a series of updates that transform your Darkness Dimensions.
4.4★ galaxyhas ending
(the) Gnorp Apologue
Also pure numbers
Strike a rock for shards and hire a growing crew of gnorps to smash and haul them, stacking synergies until the numbers explode.
96% steam
拖拖拉拉小菲镇
Also physics
Drag and fling crowds of chibi VTuber fan characters into jobs to gather resources, research and upgrade a growing town, with ragdoll physics.
97% steam75% idle
Dwarf Eats Mountain
Also physics
Send dwarves and war machines to chew through mountains for gold and artifacts, then upgrade the operation to take on bigger peaks.
4.4★ galaxy
Cell to Singularity
Also science
Evolve life from a single cell to a technological singularity, with a surprising amount of real science in the tooltips.
89% steam70% idle
Idle Lab Rats
Also science
Buy rats, train them in mazes and with lab equipment, and submit the best ones for grant money to expand your lab.
4.3★ galaxy
Cauldron
Also pure numbers
A young witch grinds minigames for resources that power up her party, uncovering the map through turn-based fights and huge skill trees.
96% steam