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Posted by patrickhulin 2 days ago

Reverse Engineering SimTower(phulin.me)
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

165 points | 29 commentspage 2
cortesoft 5 hours ago|
I love SimTower, and one of the reasons I keep my SheepShaver environment working is so I can still play it on Mac OS 9.

I’ll have to check this out!

EdwardDiego 3 hours ago||
I sunk ages into "the world's most brutal elevator simulator" - how does the game model elevator demand? I always wondered if it was some sort of Poisson distribution.
efromvt 7 hours ago||
Can you still build a garage in the bottom corner to get more starting money??
Dwedit 4 hours ago||
I remember that SimTower (Windows 3.1 version) would briefly draw the dialog boxes in Japanese, then immediately redraw it in English. This was on a computer without any Japanese fonts.
ryeguy_24 9 hours ago||
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.
findalex 10 hours ago||
I loved this game so much. Can't wait to see Santa.
taejavu 10 hours ago||
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 8 hours ago|
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.
schnebbau 10 hours ago||
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.

SuperNinKenDo 7 hours ago|
God I loved this game back in the day. Thank you!

EDIT: Nevermind... [sigh]

I_am_uncreative 6 hours ago|
What's with the edit?
cozzyd 6 hours ago||
Judging from user's posting history, they're not the biggest fans of llms

This is kind of the perfect use case though -- it's a game who cares if it's right or not.

DonaldPShimoda 5 hours ago||
Some people also have moral issues with LLMs. If the poster is such a person, the accuracy metric may simply be irrelevant.
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