Under rating threshold (hideshow)
Two minor issues:
1. In Multi mode there's no visual differenc between 6 and 8 when you mark possible numbers
2. It'd be great if you were able to somehow mark the squares (where you already put all possible numbers)
Under rating threshold (hideshow)
Text is far too small too read, and window resize is disabled. This makes it unplayable for those of us with visual impairments. 1/5 for being unplayable - There's no excuse for disabling the resizability.