After years of leaving the PBBG scene (was very active till 2009), I came back to have a look and was surprised everything is still running PHP based legacies.
So I wrote an engine. It migrates from McCodes2 and GangsterLegends V2 in one go.
It has four operational modes v2, mccodes, framework (plain engine) and GL3 (hybrid).
It uses bigint so numbers are infinite in size. Also it migrates the old way of dealing with password to a much more modern Argon2Id.
No way to double spend either, there is a message bus and a queue system.
It's open source under MIT license, so do what you want with it, you can find it here https://github.com/GL3PBBG/gl3
On the repo you find links to docs, the site, a demo, etc.
Enjoy!