Build it in the oak, then test it

Snap planks, posts, braces, rope ladders and roofs to the branches of a huge old oak, then press Test: teddy bears and a goat climb up, the wind blows, and you find out whether your treehouse holds.

Play Now

Genre: Treehouse building
Controls: Touch
Mouse
Keyboard
Devices: Desktop
Tablet
Mobile
Released: 2026

Did you like Treehouse Builder?

Treehouse Builder

Treehouse Builder is a cosy physics building game set in one huge old oak, seen from the side under a leafy canopy, with birds hopping along the branches and a swing hanging from a low twig. Pick a piece from the tray, planks for platforms, posts, diagonal braces, rope ladders, a slide, a rope bridge, walls, a window, a pitched roof, a pulley bucket, lanterns and flags, and drag it out from a knot on a branch or from a piece you already placed. A ghost shows where it will land, green when it fits and red when it does not.

Press Test and a parade of cuddly visitors, teddy bears in four colours and one rather heavy goat, walks in, climbs the bark or your rope ladder and stands on the platforms, and then the wind picks up. The structure is worked out by a real, step-by-step physics simulation that gives the same result on every device: planks need support at both ends or a brace underneath, loads travel down to the branches, and an overloaded plank bends, creaks and finally droops, tipping its visitors gently into the piles of leaves below. Nothing breaks and nobody gets hurt, and Back puts your build back exactly as it was. Forty brain-teasing challenges on the same oak ask you to reach a high branch, hold six visitors on one deck, join two platforms with a rope bridge or build a room with a roof, all within a wood budget, with three stars for the goal, for staying under budget and for not a single droop.

Free build has no budget and no goal, so you can relax and build the treehouse you always wanted, then switch to decorating with lanterns, bunting and eight paint colours. Keep up to twenty treehouses in your browser and press Photo to save a picture of your favourite. Undo and redo go fifty steps back, there is an eraser, R turns a piece, and the zoom buttons or a pinch bring you close to the knots. It works with a mouse, a finger or the keyboard.

Tips for Treehouse Builder

Treehouse Builder is about support. A plank needs something under both ends or a brace beneath it, and every load travels down to the branches, so build close to strong branches and add diagonal braces under long platforms. If the ghost turns red, the piece will not fit there, so move it before you let go.

Think about the visitors before you test. Teddy bears are light, but the goat is heavy, so a deck that has to hold everyone needs extra posts or braces. An overloaded plank bends, creaks and then droops, and a droop costs a star, so test early and watch where the structure sags. Back puts everything where it was, which makes it easy to add one brace and try again. Remember the wind that follows, and keep an eye on the wood budget: once the goal works, see whether you can remove a piece and still hold up. Free build has no budget, so try ideas there first.

Frequently asked questions

Is Treehouse Builder free to play?

Yes. Treehouse Builder is free to play in your browser on Kiloo, with nothing to download and no account needed. You can keep up to twenty treehouses in the browser you play in and press Photo to save a picture.

Can I play Treehouse Builder on my phone?

Yes. On a phone or tablet you drag from a knot with a finger to build, and pinch or use the buttons to zoom. On a computer you can use the mouse, or the arrow keys, Enter to place and Delete to erase.

Why does my treehouse droop in Treehouse Builder?

A plank droops when it carries more than it can hold. Give each plank support at both ends or a brace underneath, so the weight of the visitors, especially the heavy goat, travels down to the branches.

What happens when I press Test?

Teddy bears in four colours and a heavy goat climb up and stand on your platforms, then the wind picks up. If a plank droops, the visitors tip gently into the leaves. Nothing breaks, and Back restores your build.