There are 101 games documented on PixelatedArcade supporting Unexpanded.
Unexpanded is part of the category VIC-20 Memory Expansion Required.
The Commodore VIC-20 included 5 KB of RAM built in and it was possible to increase the amount of RAM through the use of memory expansion cartridges. Games with the Unexpanded attribute could be run on a stock VIC-20 which did not have any memory expansions installed.