It isn't his own work apparently, he copied the simulation and removed the GPL license statement.

It is his own work apparently.

`The simulation is from my own micropolisJS (http://micropolisjs.graememcc.co.uk and https://github.com/graememcc/micropolisJS) just stripped of the GPL License headers and attribution.`

It's not the same guy. He does give credit in the README, but still wrongfully stripped out the license information.

https://github.com/lo-th/3d.city/blob/gh-pages/README.md

"Start with the excelent port of Micropolis by graememcc"

It is not necessary, that it is the same guy. When graememcc adds a new license to his own work, than he can do it and an other person can use this license with agreement of the first author.

UPDATE: As much I see now, it seems that graememcc did not consent in using his work with altered license. So it is a violation.

There are three pieces of software. Each software was written by one person.

Micropolis is gpl'd.

MicropolisJS is a version of that, and is also correctly licensed.

3DCity - the submission here - is written by someone else. This person stripped the gpl headers and re-used some code without correctly licensing that code.

No! The author of MicropolisJS did not strip the licence. You are mis-reading that post.

lo-th is not graememcc.

All the source code is available, and the previous work is cited, so how is this a violation of the license?

That is not the same person as the one who made the 3D.CITY game.