Reverse Engineering SimTower

This is the story of building https://towers.world, a ~perfect, tick-for-tick reproduction of 1993 game SimTower.

I spent weeks reverse-engineering the original EXE and writing up a detailed spec of how the simulation actually works under the hood — population flow, elevator AI, the whole star-rating system. The specs are all on GitHub if you want to read them: https://github.com/phulin/tower-together/tree/main/specs

It's also collaborative. Multiple players can connect to the same tower, the simulation keeps running as long as anyone's connected, and build actions sync across clients in real time.

Because I rebuilt the UI, I could add features like shift-click to build grids of rooms - instead of painstakingly clicking to build rows of offices and hotels, shift-click allows a 10-floor grid to be built all at once.

The game runs on Cloudflare Durable Objects, one of my favorite web primitives.

Everything is open source: https://github.com/phulin/tower-together

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jlev1 2 hours ago | parent | next [-]

Wow!

There was a little-known sequel to SimTower called Yoot Tower (named after Yoot Saito). It was a commercial flop, but I played it in the 2000s and again in the 2010s and very much enjoyed it! It had a lot of added customizability (more choices of restaurants and shops, for one thing). I would love to see that game recreated.

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pixelcort an hour ago | parent | next [-]

One of the maps in Yoot Tower is Kegon Falls. When I moved to Japan I found out it was a real place. Just took another day trip up there last month. Of course IRL it’s just an elevator but the view each season is amazing.

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thispbowden an hour ago | parent | prev [-]

Love Yoot Tower! Can we clone it next?

	▲	patrickhulin an hour ago \| parent [-]
		yes! I've been thinking about how to do it, but it will take some work!

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findalex 3 hours ago | parent | prev | next [-]

I loved this game so much. Can't wait to see Santa.

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taejavu 3 hours ago | parent | prev | next [-]

Very cool! I used to play this game for a few minutes every morning at a friends place before school. With the clone being open source, would you be open to QoL patches? I don’t have anything specific in mind, just curious how close to the original you want to stay.

	▲	patrickhulin an hour ago \| parent [-]
		Patches are welcome, especially for UI stuff - the simulation I'd like to keep matching exactly. I have one deviation already: the floors are 0-indexed and lobbies are on 15, 30, ..., which would be 16, 31, ... in the original game.

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ryeguy_24 2 hours ago | parent | prev | next [-]

Oh my gosh, this really brought me back. Haven't played that game in 30 years. What a great use of AI. Thanks for the trip down memory lane.

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schnebbau 3 hours ago | parent | prev | next [-]

Amazing, loved this game when I was younger. I would keep restarting every time I thought of a more effective layout.

I don't think I ever made it to the cathedral though.

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yesitcan an hour ago | parent | prev [-]

> I spent weeks

Don’t you mean the LLM did?

This post also reads a bit AI-generated.

	▲	iamjs 38 minutes ago \| parent [-]
		This is an unnecessarily rude, dismissive, and low value comment. I loved this game growing up and I think it's fantastic to see this work. I don't find it particularly relevant whether or not a language model was involved.