Five Days is yet another rubbish Nice Code game.
Tilemaps for an alternate version of the game's title can be found in the decrypted ROM of Waixing's distribution of the game from 0x07E2 to 0x07E5. As Nice Code has been known to republish some of their games with different titles, it's unknown if the "FALLING" title was left over from a prototype or if it's used in an alternate version of the game.
Several alternate versions of this game exist which replace the graphics and, in the case of Penta Base, the music. Strafe adds a 2 player option missing from all of the other versions.