That can be tweaked; moddable, customizable. (adjective)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "tweakable" in a sentence
"From there, Rafaël finalizes the sketch, finds sounds, chooses colors, and make a rough animation and writes down what he wants, incuding what should be "tweakable"."
"The models are not proving to be very good at prediction, they may be "tweakable" to give a reasonable representation of the past, but that isn't of much use to us if they can't predict the future with a reasonable degree of accuracy."
"DFI has continued this mindset and still offer some of the most "tweakable" boards out."