X-Men (NES)

X-Men is an NES game based on the popular Marvel series. Bub.

Hidden message
As it turns out, the clue to reaching the game's final stage was hidden in the post-stage text, which would explain the kooky wording as well as a glaring typo. The message was disguised via a secondary lettering set which shared the same color as the main one, and is revealed in its entirety in these retouched images.

So the full message is thus:

The last mission can be reached from the mission screen by pushing SELECT and seek the advice of the label to make it to the final mission.

Per reference to the 'label', the remainder of the code, '+B+UP TOGETHER WITH START', was printed on the lower-right corner.

To view these messages you need to kill 30 special enemies in each stage (they have different color mapping, but not always). After that letters will be red.

The counter for this is stored at in NES memory.