Kamuo has said on his Patreon that he's basically working on 5 projects at once. AGRSS, CRIMR(his Vel pixel game), an ankha animation, and 2 projects that he is calling "Bea" and "Maiden". Bea is a short game, and Maiden is apparently the opposite of AGRSS where its simpler and quicker to do (his words).
The reason this game has been so much on the backburner is because it's his biggest project and takes the most time to do. Also apparently he said on his Patreon that he's remaking AGRSS, or at the very least overhauling it, as he's not happy with how it's turning out. So that's another big reason there hasn't been an update in a while. Although I will say, I wish he would just pick something and stick with it until it's either finished or in a good state to stop working on it. He keeps swapping projects and creating new ones without following through on his current ones and its overloading him, causing things to be released very very slowly. Hopefully he can find a good rhythm.
Good news is, he posted recently that the 1st build of the remake should be released soon. Here's hoping it's sooner rather than later.