Galactic Revenge is a homebrew game designed by MikGames and the first place winner of the SMS Power! 2018 Coding Competition. The game is similar to Gremlins 2 on the NES but has its own style to distinguish itself. The player controls Olivia Gun, out to retrieve her stolen Sega Master System from thieving aliens. I originally came across this game for Mystery Tournament challenge research and enjoyed my time playing this casually since it's a short and sweet game.
Run notes
- BizHawk version 2.7
- SMSHawk core
- Hardest difficulty (Hard mode, 1 starting heart)
- Takes damage to save time
Technical notes
For the most part the game checks for inputs every other frame, or 30 frames per second. However if there is lag then the input check takes longer at every 3 frames, or 20 frames per second, or every 4 frames, or 15 frames per second. BizHawk doesn't detect when player input is ignored so I assume all lag handling is done internally while BizHawk just assumes there's no lag. This was a recurring problem when trying to find the right inputs, mostly for the fact that there can be an odd amount of frames between accepted inputs and I couldn't just check every other frame.
General movement
Olivia's ground movement are added together, so diagonal movement and cardinal movement will take the same time in straightaways. Olivia's jump distance reaches a little over 2 small floor tiles. Since jump time is fixed sometimes ground movement has to be stopped in a given direction before making the next jump across platforms to avoid getting hit.
Damage boosting
Getting hit sends Olivia backwards in whatever direction she was facing upon getting hit. The knockback distance is a little more than 3 small floor tiles. This knockback briefly ignores pits for its duration and is used to skip a few parts that would require either extra movement or extra waiting.
Outfits and shot types
For the first room of the game Olivia gets to use the space suit, which allows for shooting across the entire screen and 3 shots on screen at a time. She is forced to downgrade to the shinobi outfit with shurikens which have a limited range and limited to 1 projectile on screen at a time. In this run I get 10 coins to buy the fire suit which shoots 2 fireballs at a time in a V shot pattern and allows for 2 projectiles on screen at most. Another volley of shots can't be used until both fireballs are off screen. The other suits cost too much to get quickly and do not have enough benefits to warrant obtaining them in a timely manner.
Close quarters cancelling
If Olivia is close to an enemy, then they will not shoot bullets at her. The main strategy for taking out enemies quickly and safely is to rush up to them and start blasting. This also applies to bosses as well and is utilized to the fullest extent.
Difficulty changes
The game is initially set to Easy mode with 3 starting hearts. The most obvious change in Hard mode is that everything has a lot more health and is harder to take out without stopping. This results in me ignoring enemies past a certain point due to their tankiness, even with the lag they can generate. The starting hearts mostly affect what opportunities I can use a damage boost so setting it to 1 is just a slight limiter.
Enemy drop RNG
RNG seems hard to manipulate and might be affected by the game difficulty to reduce heart drops. This resulted in getting only 2 extra hearts, and thus only 3 damage boosts that I could utilize throughout the run. Coin drops were probably also affected but the amount I grabbed wasn't a big issue. Larger foes can drop multiple items including hearts but I never managed to get any heart drops from them in this run and worked around that for the latter half of the run.
Memory addresses
All addresses listed were found with BizHawk's RAM tools.
| Domain | Address | Size | Signed | Endian | Notes |
|---|
| Main RAM | 100B | 2 byte | Unsigned | Little | The player's X-position in the current room. |
| Main RAM | 100D | 2 byte | Unsigned | Little | The player's Y-position in the current room. |
| Main RAM | 100F | 1 byte | Unsigned | Little | The player's Z-position, or current jump height |
| Main RAM | 1897 | 1 byte | Unsigned | Little | HP of enemy in slot 1, used by all bosses and most minibosses. |
| Main RAM | 18AF | 1 byte | Unsigned | Little | HP of enemy in slot 2, mostly used for the 2nd twin of the Twins boss. |
Level notes
The run will be explained room by room. The game's page says there's 20 stages, which is a little less than the number of rooms listed but accurate enough.
Room 1
This is the only room where the space suit is used. A few coins and a heart was gathered from the enemies taken out along the way. The space suit's range and projectile limit means that the miniboss blocking the exit is taken out without stopping at all. This miniboss shows up a few more times but will take more time to take out throughout the rest of the run due to range and shot limits of the other suits.
Room 2 - Changing room area
The space suit is dropped due to its weight according to the plot and is swapped out for the more limited shinobi suit.
Room 3
The first moving platform appears and unfortunately needs some waiting to reach. The robot at the end isn't blocking the exit but taking it out seemed to adjust the item drop RNG a bit further.
Room 4
This first room with conveyor belts within them. I take advantage of conveyors moving towards the exit as much as I can. I gather the last heart I managed to get as an item drop here. An extra slime is taken out to advance the item RNG. The miniboss shows up again and takes longer due to the limitations of the shurikens.
Room 5
The robot is taken out while waiting on the moving platform, dropping a coin that is taken.
Room 6 - Big Slime boss
The big slime is easily carried to the corner with rapid fire shots and taken out swiftly. The coin drops are ignored.
Room 7
A single coin is gathered here. A laser bot is manipulated to walk to the right to slip past them. Another miniboss shows up and is taken out.
Room 8
Two skulls are taken out while waiting on the moving platform to prevent being knocked back into the pit.
Room 9 - Elevator 1
The elevator ride is just a timed segment about avoiding bombs. I try to make it a little interesting with close calls and other silly bits of running around the room. I could have left the room later but exiting the room before the text box closes but it messed with input timings and some platform cycles.
Room 10
The spinning maces are approached to avoid having to wait on the moving platforms for crossing the pits. Another laser bot is manipulated to move out of the way. There's a miniboss at the end that's taken out like the others.
Room 11 - Twins boss
The right twin is taken out first since they stand still and shoot. The shots are cancelled by just approaching them to force them to stop. The coins dropped by the other twin are gathered before heading out.
Room 12
There are a few tight jumps here and there to skip having to take some conveyors.
Room 13
A damage boost is taken to save a bit of time. The walk bot, who is actually a demoted boss, is manipulated to walk a little bit away from the shop to avoid taking 2 hearts of damage. A fire suit is bought to handle the rest of the game with the double shots. Another damage boost is taken to save a little more time from going around the room.
Room 14
There's an optional minigame in this room. It is promptly ignored since it's also deliberately not great.
Room 15
A damage boost isn't enough to skip the pit so the 3 moving platforms section has to be waited on. However the swinging mace is used to skip a moving platform waiting cycle a little bit up in the road. This is the last damage boost I managed to utilize.
Room 16 - Pods boss
The fire suit makes quick work of this boss, which would be a huge pain with the shurikens, fast boss movement, and small hitbox.
Room 17
It's a little faster to walk on the conveyors for a little bit than to repeatedly jump due to the fixed air time.
Room 18
Time on the conveyors is maximized as much as possible. It's slightly faster to walk around the slime at the end rather than shoot it down.
Room 19 - Elevator 2
It's another elevator waiting section. I did manage to get the faster exit this time and it didn't seem to make cycles worse.
Room 20
If I had just one extra heart to space the beginning of the room could be sped up by taking a damage boost to reach the rightmost conveyor at the start. Otherwise there's the last miniboss taken out with a fireball volley.
Room 21
More conveyor belt usage and bullet dodging for an otherwise straightforward room.
Room 22 - Meka boss
This boss looks vaguely like the Meka dragon from the Wonder Boy series. They shoot a lot of dangerous bullets and move swiftly, but is taken out like the rest even with its larger health pool. Fun fact: the game cuts off continues for this fight and forces you to restart from the beginning of the game if the player gets a game over. Guess how I found out.
Room 23 - Sega Master System storage
The Sega Master System is retrieved with some celebratory jump shots and the back exit is taken, ending the game
Potential improvements
- Better understanding of the lag handler of the game could help with lag management
- Better item RNG understanding for more heart drops can save some time with damage boosts, most notably the start of room 20
Special thanks
- Mike Ruiz for making this neat game and submitting it for the coding competition
- SMS Power! for hosting these cool competitions to showcase the fan efforts expressing their love of the Sega Master System
Truncated: I think this game surpasses the minimum threshold of game quality for a homebrew by quite a bit, and the game is complete and original (though heavily inspired by Gremlins 2).
The movie quality is also good, nice movement and interesting damage boosts. Accepting for publication!
For anyone wanting to improve this movie in the future, two areas to check would be:
- Investigating how the RNG works and how to manipulate more health for shortcuts over pits - playing casually, I got two health refills in the first room several times, this movie only gets one.
- Seeing if more enemies can be killed to decrease lag, since it's very heavy in some areas.
