I kept the on screen instruction as the same, now you can have use E and also F. I fixed the issue of GPU usage, I had no idea about the GPU usage issue, but due to your feedback I changed it. I will push the update once the build is completed! Thank you very much for feedback!
As for the save feature, I am still learning I really don't know how to implement it, cause the way my game is built having that feature will cause alot of issues. In my next projects I will add the save feature for sure!