Microsoft made sure in windows 10 that it's almost unusable without SSD. SO you big binary blob file have random r/w access. Most backup software is able to do

Microsoft made sure in windows 10 that it's almost unusable without SSD. SO you big binary blob file have random r/w access. Most backup software is able to do good binary deltas of arbitrary data for decades. Even dumb checkpointing resolves problem of downloading 25 versions - you download latest checkpoint and deltas from there. Don't excuse poor design and programming, when you know a file structure, creating a differential update should be short task. With a tiny bit of algorithmic knowledge you could even optimize the process to only download needed assets inside of you big binary blob - if the asset was changed 7 times during your last 25 version you only need to download the last one.