Isolated Warrior

Isolated Warrior is an NES game by Vap.

Unused sprites
The US version contains a couple of unused enemy sprites. These were mostly removed in the Japanese version to make room for a set of Japanese characters, which would seem to indicate that the US version was developed first (extremely uncommon at the time).

Snake


This snake-like enemy (boss?) would have appeared somewhere in stage 4. It can be seen by changing ROM address to  and using the password 0705.

Unfortunately, the sprite's programming is either incomplete, or requires background elements/sprites not present in the final level to control its behavior (a rail, perhaps?). As soon as it appears, it locks onto your position and jumps towards you in a slow arc. When it hits the ground, it explodes, sending eight segments flying in different directions. Each segment can be destroyed with either normal shots or bombs, though they never seem to drop anything.

Depending on where the sprite is placed, it may either explode in mid-air or cause the game to lock up/reboot. Very peculiar.

Armored thing


This appears to be an ordinary enemy, which may have been used in a high-speed level (the river or the city streets), judging by its VROM location. No sprite IDs tested thus far seem to correspond with this enemy, so it may be lost for good. Too bad.

Unused graphics
This unused KID logo (Kindle Imagine Develop, the game's developer) was found amongst the cutscene graphics in the ROM.

Hidden cutscene graphics
The space station in the stage 5 cutscene is actually a bit larger than it appears on-screen. The game normally applies a letterbox effect, cutting off the top and bottom of the image. FCEUX's name table viewer reveals the whole scene.

Secret passwords
All of the game's valid passwords are stored at in the ROM. Most of them start you at a given stage/difficulty level, but the last few have some special effects:


 * 6502: Full HP and bombs
 * 6285: Full weapon power
 * 6666: 1 HP
 * 5350: Invalid, no effect (password routine bug; should stop checking at 6666)

Note that using any of these passwords will lock you out of stage 7 (continue flag =).

Debug flags
RAM address activates two debugging features:


 * : Invincibility
 * : Full weapon power (permanent) and level 5 bombs (reset between lives)
 * : Both of the above

No code in the ROM ever writes to this address!

Leftover Sound Test Text
The text strings SOUND TEST, BGM NO, and EFT NO can be found at in the ROM file. Presumably, the game contained (or was supposed to contain) a sound test at some point during development, but no code points to these strings in the final version.