i was able to reach level 49 but unable to pass beyond that, i tough it was a bug but it seems like it's actually were the game ends. The game itself is kinda fun, i wish there where more variations and actually being able to beat the game.
I do have this one, the Famicom one, and the arcade version on the Taito PS2 compilations. Sad to see this one has a game ending bug, can't clear level 49, leaving a feeling of dissatisfaction behind.