I'd like to recommend this version of free Sudoku for the Kobo Vox:
If you have acecss to the Android Market:
https://market.android.com/details?i...ver.free&hl=en
The developer website:
http://www.1gravity.com/index.php?op...d=74&Itemid=71
Or a direct download:
http://androiddev.orkitra.com/downlo...ver.free_v1.00
I had to download to my computer and transfer over via USB to install only because the androiddev website is, as noted earlier, a bit flakey.
I have already managed to waste several perfectly good reading hour playing this Sukodu instead ...