---
url: "https://www.reddit.com/r/vibecoding/comments/1vgc9sw/i_created_sandcastle_simulator_with_opus_5/"
title: I created Sandcastle simulator with Opus 5.
source_kind: reddit
subreddit: vibecoding
author: oxmannnn
score: 267
captured: "2026-08-06T07:08:12+00:00"
comment_tree: false
topics: [ai-tools]
summary: User created an open-source sandcastle simulator in ~8 hours using Opus 5 on Ultracode mode, mostly from a single prompt.
status: ok
---

~8 hours of work. Opus 5 on Ultracode mode. And yes, it's open-source.
I made this 99% with a single prompt. After that I just added various cool little things, like different textures ("looks") and other cool effects.
Here's the repo+demo: https://github.com/winchxyz/tidewright