Why Animal Well Bet on a Custom C++ Engine: The Handmade Stack Behind a 90-Score Puzzle Labyrinth

Short answer: solo developer Billy Basso built Animal Well from scratch in C++ with no existing engine because he wanted to understand and control every system and ship only code the game actually needs. That 7-year bet produced a 35 MB Steam build (48 MB on Switch), pixel-perfect jump feel, and a secret-dense Metroidvania where every toy has three jobs and half the game hides after the credits.

Animal Well is a 2024 Metroidvania puzzle-platformer developed by Billy Basso as Shared Memory and published by Bigmode, released for Switch, PS5 and Windows on May 9, 2024 and for Xbox Series X/S that October Wikipedia. Developer credit is listed as Billy Basso and publisher as Bigmode, with platforms Switch, PS5, Windows and Xbox Series X/S Wikipedia. The store pitch is simple: hatch from your flower, spelunk a beautiful and sometimes haunting pixel world, meet helpful and ominous creatures, and unravel secrets with unconventional upgrades Steam. Nintendo describes the same loop as explore, solve, survive — illuminate the dark, observation is rewarded, you are disempowered and must make clever use of environment and items Nintendo.

That disempowered part matters. This is not a combat Metroidvania.

What the game actually is

You control a small yellow blob with no plot or backstory, exploring a 16 by 16 grid of flip-screen rooms with low-resolution pixel art Wikipedia. One room is visible at a time, connected into a labyrinth with obvious and hidden connections Wikipedia. You walk, jump, collect toys — slinky, frisbee, bubble wand — plus firecrackers to scare animals and matches to permanently banish ghosts from a room Wikipedia. You start with four hearts, restore them with pink fruit, and can earn four extra blue hearts Wikipedia. If you lose them all you respawn at the last telephone you touched Wikipedia.

The gating is classic Metroidvania with a twist. In four locations colored flames sit behind large animals you must defeat with the local environment, then carry to a central room to open a new passage to a wraith-like manticore Wikipedia. Destructoid describes the same structure as explore to collect all four flames marked on the map, with the map showing every room and route so you can hunt the path not taken Destructoid. The item list sounds like a toy box: Bubble Wand to make a bubble and hop gaps, Disc to hit hard-to-reach buttons, Slink for puzzles that seem to need two of you, Yo-Yo as chaos tool Destructoid. Every item has several uses you must work out by experiment Destructoid.

Eurogamer makes the same point without spoiling specifics: you pick up unlikely objects with one delightful use, then they reveal multiple other equally delightful uses as you push against impossibilities Eurogamer. Rock Paper Shotgun calls them tools in quotes — frisbee, bubble wand — straightforward on the nearest obstacle and rich with elaborate uses an hour later when you revisit RPS. There is no combat at all. Bosses are beaten with knowledge, not damage Destructoid. The ghost cat chase is a puzzle to trigger and a gauntlet to survive with no cinematics or special moves, just skills and world knowledge Destructoid.

Then the game keeps going. After the first ending there are three more layers: a second layer for discovery players requiring secret areas and hidden eggs, a third layer with hidden bunnies and alternate-reality-game elements including one puzzle requiring at least fifty players combining partial solutions, and a fourth layer with repeat-playthrough challenges like speedrunning and undocumented actions Wikipedia. Publisher Bigmode told reviewers that seeing the credits means you have seen about half of what the game offers RPS.

Reception matched that ambition. Metacritic lists Animal Well as Metroidvania from Shared Memory, released May 9, 2024, with Metascore 90 Universal Acclaim from 30 critics and user 8.0 Generally Favorable Metacritic. Steam highlights 10/10s from Destructoid, Eurogamer and Noisy Pixel, including Eurogamer's line about being astonished by how deep it goes Steam. Wikipedia records Outstanding Achievement in Game Direction at the 28th Annual D.I.C.E. Awards and nominations at The Game Awards 2024, the 25th Game Developers Choice Awards and the 21st British Academy Games Awards Wikipedia.

What “custom C++ from scratch” means here

Basso did not use any existing game engine, instead building the entire project from scratch in C++ as he wanted to understand and be in control of the underlying systems and only have elements in the code that applied to Animal Well Wikipedia. He developed the entire game himself, including the underlying engine Wikipedia.

That is the opposite of the default 2024 indie choice. Unity, Unreal or Godot would have given him an editor, physics, animation, UI, asset store, console exporters and a forum when something breaks. Basso traded all of that for monopoly: one brain owns the renderer, the physics, the save format, the map grid and the animal logic.

The footprint shows it. Steam lists minimum 1 GHz processor, 1 GB RAM, integrated graphics, DirectX 12 and 35 MB available space Steam. Nintendo lists 48 MB for both Switch and Switch 2 Nintendo. Price was $24.99 at launch Destructoid Steam.

Context matters for that timeline. Basso began development in 2017, his first solo work after mobile work at Phosphor Games and NetherRealm Studios on multiplayer free-to-play games Wikipedia. He started it as a side project focused on gameplay systems first, world afterwards to justify them, inspired by Super Mario Bros. 2, Metroid, Zelda, plus Fez, The Witness and Tunic for discovery and hiding secrets in plain sight Wikipedia. During the first year walks around Chicago, lawn ornaments, animal statues, overgrown spaces and his own drawings of animals and architecture fed the design; he decided early there would be no humans because animals are universally relatable Wikipedia. He named it Animal Well a year in for being descriptive but ambiguous, then spent another year inventing mechanics first and deriving puzzles from their interactions Wikipedia. He partnered with Dan Adelman after four years to handle marketing, and with Bigmode a year later as their first published game after Jason Gastrow (videogamedunkey) saw it at a festival Wikipedia. Destructoid similarly frames it as the first game published by Videogamedunkey's company Bigmode, developed by Billy Basso, released May 9, 2024 Destructoid.

Seven years, one programmer, no engine team. That is the cost side.

What the handmade stack gained

1. A jump you can trust with secrets.
Destructoid says the tight control scheme is the foundation: Basso worked out exactly how far and high you can jump and built every puzzle around that default, so everything feels fair even when frustrating Destructoid. RPS calls the jump note-perfect whether precision-hopping dangerous surfaces, mashing up a laddered chasm or leaping into a hoped-for hidden chamber RPS. When your engine owns integration, coyote time, input buffering and collision, you do not negotiate with a physics middleware update. You tune one number and every room stays honest.

2. Toys instead of weapons.
With no engine combat template to fill, Basso made items that manipulate environment in surprising systemic ways Nintendo Steam. The Yo-Yo example is telling: introduced to reach buttons around corners, later puzzles force you to realize animals are attracted to it, so they hit switches for you or reverse mechanical inputs Destructoid. That is cheaper to build when AI, items and switches live in the same C++ file than when they live in three plugins.

3. Darkness as a system, not a filter.
Eurogamer lingers on streams and lakes, a torch swinging on a chain, creepers brushing aside, a lamp's red light scattered by a waterfall — pixel art that feels new, not nostalgic Eurogamer. Destructoid notes vines that shift with a swishing animation when you run through them and creatures that look ethereal and ghost-like, making the tiny bright seed stand out in a dim world Destructoid. A custom 2D renderer with bespoke lighting and particle rules can make every lamp a clue and every shadow a potential door without paying for a 3D lighting model you do not need. The 35–48 MB size is the receipt Steam Nintendo.

4. Cheap mystery.
This is my term, and I label it as analysis, not a quoted fact. Most engines make content cheap and mystery expensive: every update, every store package, every shader graph adds code you must audit to be sure a secret is still secret. Basso inverted it. Because only code that applied to Animal Well exists Wikipedia, adding a bunny, an egg or a 50-player ARG step Wikipedia does not risk breaking an unrelated vehicle physics module. Mystery stays cheap for seven years. That is why the game can afford four layers.

What it cost

Time and bus factor. Seven years from 2017 to May 2024 Wikipedia is the headline. Needing Adelman for marketing after four years and Bigmode as publisher after five Wikipedia shows even a solo purist needs help shipping. No engine also means no free console exporters, no hired Unity generalist can jump in, and every tool — map editor, animation preview, save debugger — is yours to maintain.

It also means no safety net for discoverability. Without Unity or Unreal logos, festivals and a publisher matter more. In this case Bigmode as first published game after a festival demo Wikipedia was the distribution hack.

My take: the ignorant engine, the monopoly on surprise, and the telephone philosophy

Here is where I depart from the usual “custom engine = performance and pride” story. I think Basso built an ignorant engine on purpose — and that ignorance is the design.

Other commentary says custom C++ was about control and understanding Wikipedia. True, but incomplete. My reading: control was not about power, it was about the right to leave things out. No rigidbodies you do not use, no animation state machine you do not need, no store UI framework that teaches players to expect buttons. When the engine does not know how to do combat, you cannot accidentally make combat. You must invent a bubble wand.

Second, mystery needs monopoly. A 50-player combined puzzle Wikipedia only works if one person holds the full causal chain in their head. On a team engine with five contributors and three plugins, someone would leak it in a commit message or break it with an upgrade. Solo C++ is a spoiler vault. Basso could hide things even from his publisher because there was no dashboard to spoil them. Bigmode saying credits are only half the game RPS reads to me like a publisher delighted to be kept in the dark too.

Third, the telephone is the engine philosophy in one object. Telephones are save points and signs someone was here before Eurogamer. Respawning at the last telephone Wikipedia teaches you to treat rooms as experiments you can re-enter cheaply. Flip-screens Wikipedia reinforce it: one room, one idea, reset on exit. My unrigorous but useful mental model is well as database: 16×16 rooms, deterministic animal traits that plug into single-screen puzzles RPS, wordless teaching without text RPS. Unity streams worlds; Basso queries rooms. That is why observation is rewarded Nintendo is not marketing — it is a query instruction.

If I am wrong, I am wrong in an interesting way: even if Basso could have built the same game in Godot in four years, he could not have thought the same game in Godot. The tool shapes the puzzles you dare to hide. An engine that can do anything tempts you to add everything. An engine that can only do what you wrote tempts you to notice what you already have. The finger-post revelation Eurogamer describes — obvious only in hindsight Eurogamer — is the payoff of that constraint.

What indie devs can actually steal (without rewriting everything in C++)

• Mechanics first, world to justify them. Basso prioritized systems, then crafted the world to justify them Wikipedia. Prototype one toy with three uses before you build a biome.
• Budget mystery like content. If you want post-credit layers, keep your dependency count low enough that a secret added in year six does not break year two. The 35 MB footprint Steam is a proxy for auditability.
• Tune movement before puzzles. Lock jump height/distance as law, then build rooms around it Destructoid RPS. Players forgive being lost; they do not forgive feeling cheated.
• Make disempowerment fun. No combat Destructoid, tension over action Nintendo, assess safety yourself Nintendo. Firecrackers and matches Wikipedia scare or banish instead of killing — cheaper to balance, scarier to use.
• Teach without text. Single-screen puzzles that broadcast wall differences and reuse noticed patterns Eurogamer, dispersed multi-screen machinery that joins across biomes RPS, plus a map that fills as you light candles Steam Nintendo. Wordlessness RPS is localization for free.

Train the same muscles in your browser

Animal Well rewards two habits: seeing a tool's second use, and connecting clues across rooms while taking notes — RPS even mentions a pencil to scribble on the map and a game where you will want to take notes RPS.

If you want a quick trainer for the first habit, try Bad Ice Cream. You collect fruit in maze levels while creating and breaking ice walls to block enemies or open shortcuts. Like the Bubble Wand and Disc, ice is never single-purpose: the same wall that saves you can trap you if you overbuild, so you learn to ask what else a tool can do before you commit.

For the second habit, Rooms Home Escape is a calm, direct fit. You explore a locked house, collect tools with more than one purpose, and link a note in one room to a pattern in another — observe before acting, keep notes, revisit old rooms when stuck. That loop is Animal Well without the darkness: small grid, big connections, aha when two unrelated clues click.

Both run instantly in browser, which makes them useful warm-ups before a longer, note-heavy Animal Well session where the main game is just the beginning and players will be discovering hidden puzzles for years Steam.

Bottom line

Animal Well did not succeed despite a stubborn custom C++ engine. It succeeded because stubbornness was the design: one owner, one mental model, only code that matters Wikipedia, tiny builds Steam Nintendo, precise movement Destructoid RPS, toys with hidden depths Eurogamer Destructoid, and layers that demand collaboration Wikipedia. Unity could have shipped a Metroidvania faster. Only a handmade well could hide this much water.