Each one lent under a licence that lets a free game use it. 2 of those licences ask for a notice in return, and this is it.


The notices these licences require are reproduced below, as their authors wrote them.
facesjs: Copyright 2017 Jeremy Scheff. Licensed under the Apache License, Version 2.0.
Dexie.js, by David Fahlander. Licensed under the Apache License, Version 2.0.
The licence text is at apache.org/licenses/LICENSE-2.0.