What are some alternatives?
When comparing MASGAU and Steam Library Manager, you can also consider the following products
GameSave Manager - Ever had to format your system?
Steam Mover - Do you have a super-fast SSD that is too small to hold all your steam games at the same time? Then try Steam Mover.
Game Backup Monitor - Automatically backup your saved games with optional cloud support.
Open Game Panel - OGP is a game server control panel.
SaveGame Backup Manager - The target of the project is backing-up full savegame settings including registry keys.
Bright Game Panel - Bright Game Panel is a free and open source game server control panel.