For PC emulation via Xenia, highly compressed ISOs are not recommended because:
You cannot just double-click a compressed ISO. You need specialized hardware or software. xbox 360 games iso highly compressed
Many users seek ISOs for use with Xenia, the Xbox 360 emulator for PC. For PC emulation via Xenia , highly compressed
Many Xbox 360 games used "dummy data" to fill the disc. Tools exist to trim this empty space from the ISO. You cannot just double-click a compressed ISO
In some regions, it is legal to create a personal backup of a game you physically own. However, downloading someone else's backup—even if you own the game—is generally not covered by this exemption.
For most users, emulation is safer and easier. Use Xenia (the leading Xbox 360 emulator).
If you are looking to manage your own game backups to save space, here are the legitimate technical methods used by the community.