Tag Archives: NES games

GUEVARA WAR (NES Hack) And Death Flags.

29 Apr Guerilla War NES Hack
Guevara War NES Hack

Guerrilla War is the 1988 NES port by SNK of their arcade run-and-gun title. Superficially it has a lot of similarities with their other overhead run-and-gun titles like the Ikari Warriors franchise. Interestingly the original game, Guevara (“ゲバラ”), follows the path of Che Guevara and Fidel Castro liberating Batista’s Cuba. The text of this plotline was naturally removed in North American localization in Reagan’s America, but otherwise the map and plot was the same.

This is my first NES ROM hack, a graphic and text hack restoring the original plot in the English version. I replaced the pixel art image of the Cuban revolutionary with a digitized photo as well as changing the text. I restored the player names to GUEVARA and CASTRO as in the original. I also replaced the in-game font with one that is more military looking. This also included a full overhaul of the title screen with a chibi anime Che Guevara I designed.

I wanted to add a couple actual game mechanic hacks, specifically the ability to keep the player’s score and weapon after death, but that proved much more complicated than initially. Tracking down where the score and weapon are stored in the RAM was the easy part (see notes below). Interrupting the routine after death that initializes the weapon (and the score after continue) is much more problematic because the address for the flag is reused for multiple functions in the overall game program. In the notes below there is a superficial Game Genie code that allows the player to keep the weapon after death, but it leads to many undesired effects elsewhere in the game code. In the end it didn’t seem like a good hack with so much potential instability. The IPS patch for the graphics hack is below:


(This is not a game ROM, which I do not have the right to distribute. This is an IPS patch (created from Guerrilla War (USA).nes) which entirely contains code and data I created. My preferred IPS patcher is Lunar IPS.)


The 8×16 font is treated as metatiles and the text using it in the ROM is stored in plaintext ASCII.

Player 1 Lives: 0x0028
Player 2 Lives: 0x0029
Next Stage: 0x0039
Player 1 Score: 0x0190, 0x0191, 0x0192
Player 2 Score: 0x0193, 0x0194, 0x0195
High Score: 0x0196, 0x0197, 0x0198
Timer For Tank: 0x04C2
Player 1 Weapon: 0x0600
Player 2 Weapon: 0x0601


000 – Normal Gun/Normal Bombs
001 – Spread Gun/Normal Bomb
002 – Laser+Spread Gun/Normal Bomb
003 – Flamethrower Gun/Normal Bomb
004 – Laser Gun/Normal Bomb
024 – Normal Bomb/Powered Bomb
025 – Powered Bomb/Powered Bomb
026 – Destruction Bomb/Powered Bomb
028 – Rescue Whip/Powered Bomb
032 – Normal Gun/Destruction Bomb
033 – Spread Gun/Destruction Bomb
034 – Laser+Spread Gun/Destruction Bomb
035 – Flamethrower Gun/Destruction Bomb
036 – Laser Gun/Destruction Bomb
073 – Powered Bomb/Rescue Whip
074 – Destruction Bomb/Rescue Whip
076 – Rescue Whip/Rescue Whip


SXUTEUSO – Keep Weapon After Death. Replaces the ASM opcode at line 0xEBB0 (the death flag routine mentioned above) which is originally set at $9D (STA: Store Accumulator) with $AD (LDA: Load Accumulator). Essentially it replaces the code that changes the weapon variable with a different command that dumps the zero value into the accumulator (a set aside register of RAM addresses where intermediate values used in arithmetic routines wind up; a sort of junk drawer in the RAM). This also affects several animation timers in the game, leading to softlocks and ghost animations.

AYSVOGEI – One Hit Kills (including bosses). Sets address 0xEC59 to 70. Can be changed to EASVOGEI, which causes bosses to have significantly reduced hit points, taking two to five hits instead of just one.

Let’s Play (And Overthink) Clash At Demonhead: Part 1. #retrogaming #NES #

30 Jun

Honestly, I have no idea why this game was so obscure when it came out and didn’t become a classic with multiple sequels for this reason alone: THIS GAME GIVES YOU A JETPACK AND A SUIT THAT LETS YOU SWIM IN LAVA. Seriously, think about that for a second.

clashatdemonhead1Don’t worry, we’ll wait.

This game is amazing and full of wacky goodness, really. Anyway, this post is gonna focus more on the “Overthink” than “Let’s Play” part because there’s already plenty of play-by-play analysis of the game these days. I just want to compile all the oddball facts about the game into one place, because there is a surprisingly large amount of weird trivia for a one-off game.

clashatdemonhead8For instance, I went decades without knowing the names of all the bosses.

Also, I’m not gonna mention Scott Pilgrim. Because, meh.

Anyway, Clash At Demonhead was a platform game released on the NES in 1989 from Vic Tokai, the communications branch of a natural gas company. Seriously. A natural gas company. Apparently EVERYONE in Japan tried their hand at making video games in the late 80s.

The game has you playing Billy “Big Bang” Blitz, a secret agent who, for some reason, looks like he’s auditioning for My Chemical Romance. In the actual game itself, at least the English version, he’s just called Bang. However, his full name is leaked in this Nintendo Power spread about the game, which also mentions a few other things left out of the translation from the original, called Dengeki Big Bang.

clashatdemonhead2Which, incidentally, had a way cooler title screen.

Sargent Bang is pulled back to duty from vacation to rescue Professor Plum, who’s been captured by an evil gang called The Lawbreakers to build a Doomsday Bomb that threatens to blow the world up. What the gang planned to do after blowing literally everything up is not elaborated upon.

clashatdemonhead3These guys can’t collaborate on a dress code, much less a plan.

The bomb is set atop a mountain that dominates the map, which is possibly part of the Bear Lodge Mountain Range. You chase the members of the gang and other assorted baddies through this map, which might be set in North-Eastern Wyoming, based Devil’s Tower being a prominent in-game landmark.This would make the dense forests in the surrounding area part of the Black Hills Forest, which are dominated by pine and hardwood trees, much like the game depicts, and the winding river would be the Belle Fourche.

clashatdemonhead4I’ve, ahem, put a lot of thought into this.

As you go along, the plot spins completely out of control with a strange series of subplots involving demons and aliens, mind control, clones. At one point you even talk to a dead guy. You recover a magic sword and board a spaceship, fighting samurai, goblins, robots, punk rockers, bigfoots, and talking skeletons and mushrooms. And that’s before you even defuse the Doomsday Bomb. This game has everything.

clashatdemonhead6even, um, this

One of the really amazing things about this game, however, is the attention to detail and revolutionary programming/gameplay elements for a game with no licensed property involved. Apparently, it incorporates whatever Variable Width Fonts are, which is apparently a super rare thing. There’s also a huge range of dialog images depending on whether you are wearing any special suits. Not only that, but the outfit you wear changes the way some of the lower level enemies act around you.

clashatdemonhead7and they apparently get increasingly sarcastic

But seriously, the game is a whimsical treat with a ton of easter eggs and definitely worth tracking down. I plan on doing a sequel of this piece sometime where I follow a playthrough I created as a teenager, where you stumble across all the cut scenes in the correct (or at least most sensible) order and you don’t repeat paths (well, you don’t repeat paths more than a couple times, there’s some situations you can’t avoid it). There will also be comparisons between this and the import version.