Absolutely engrossing. A friend sent me the link to the online version, and I couldn't help but play it wholly. Love how it blends and improves on KenKen, Sudoku, Flow, and crosswords (and no doubt other influences and new ideas). The rules are abstractly but still clearly explained, and the puzzles are nicely challenging. It's getting late now, but I'm going to replay this tomorrow just to see if there's any secrets I missed.
P.S. Is the "C P V V B D G" IVRI FDI ZMYLFX OSMNVO QVITVVF VMNZ 'C P V V B D G' intentional?
P.P.S. TZD LO NMOOMFBPM