Advanced Transformice web-client is an application which allows you to play Transformice in full screen mode with additional settings such as aligning and scaling.
git clone https://github.com/expwez/transformice-webclient.git
cd transformice-webclient
cd transformice-webclient
chromium index.html
In the folder is a file named settings.js. This file contains the default settings with lists of possible values. you just need to replace the current value in the corresponding line with any of the proposed.