This is mostly a repeat of the old submission except for missile info.
Introduction
Xanthiom is an Atari 2600 homebrew game developed by Mathan Games in 2023. The player controls Lieutenant Grisham, on a mission to rid the threats to the galaxy on the planet Planet Coati 5. This homebrew is very much a take on what the original NES Metroid would be like on the Atari 2600 with the limitations therein. I found this to be a pretty fun game and it's short enough that the lack of saving or continuing isn't that big of an issue.
The goal of this TAS is to collect every upgrade in the game before beating the game. The game remains incredibly sync friendly so redoing the boss fights was all I really had to do.
Run notes
- Emulator used: BizHawk 2.9.1
- A2600Hawk core
- 100% item completion
- Takes damage to save time
Mechanics and techniques
Delaying the start for a frame
I delayed starting the game for a frame. All this does is allow the game to render the projectiles as squares rather than lines. This doesn't seem to actually affect shot hitboxes or affect sync but it does help with visibility for the viewers.
Upgrade list
Here's a quick rundown of the upgrades in the game.
- Missile tank
- This adds 5 maximum missiles to Grisham's arsenal. Missiles do 4 damage more than beam shots so they're used to take out bosses quickly. Without the Power upgrade missiles are 3 times stronger, while with the upgrade missiles are "only" 2 times stronger.
- Energy tank
- This adds 100 extra energy for survival. This is pretty straightforward although there's no knockback. Damage is by contact over time with harmful objects.
- Jump boots
- This increases the vertical jump height from 3 blocks to 4 blocks. This is required to navigate most of the map.
- Wave beam
- This upgrade adds a vertical wiggle to the beam shot. This would help with more coverage with the beam shot but sometimes it makes the beam move in a way that would cause it to miss in situations where a straight shot would hit. It's not a great upgrade though it has to be obtained for 100% completion.
- Varia suit
- This protects Grisham from passive damage while in the second map of the game.
- Power beam
- This adds 2 damage to both the beam shot and the missiles. This is optional but speeds up the second boss fight.
Enemy HP
Enemy HP is found at address 0x60 but offset by 4 bits. That pretty much means subtracting about 8 from whatever the RAM watch says to get the HP of a given enemy.
Jumping
Jumping will always try to go for the full height of the jump. This is a problem when there are potential objects above to get caught on. Jumping can also sometimes delay when the next shot can be fired so jumps sometimes have to be delayed due to that.
Bosses
The first boss, a big green boss, can be shot anywhere on the body. The only real thing to speed it up is to get close enough to keep up a high firing rate and to end the fight as close to the Varia suit upgrade it drops when it dies.
The second boss, a mobile purple boss, can be somewhat manipulated in its shot timing with certain actions. Missiles are shot in strategic places and times to finish off the boss quickly.
RNG
The RNG in this game is pretty kind. It seems to reset upon any screen transition which makes the game incredibly sync friendly. The second boss can also be slightly manipulated by jumping on certain frames.
Glitch Discovery (Floor Clipping)
I (nymx), during my analysis of
Darkman425's submission, was noticing that jumping was being affected when hitting the edges of a floor from the bottom. Because of this, I started using it to interrupt my jump so that I could land earlier and continue my progression without the long wait in the air. Well, I did this a number of times in various places and one attempt got me lodged in the floor. At that point, I noticed you can do a 50% duty cycle jump and continue upwards...as long as the floor had another block above where you stood. After I made this discovery, I talked with Darkman and he mentioned that a map existed of the game. I used it to figure out places that would benefit from this glitch and continued cutting large chunks of frames, bypassing lots of rooms towards my next destination.
At the beginning of the game, there is a missile to the left. Trying to execute this glitch early failed...probably because of the added abilities of the "Hi Jumps" boots, which probably has the upward acceleration to skip detection and cause this to happen in the first place. If this is not the case, then it might still be possible to perform this early missile grab and cuts another huge chunk of frames.
Special thanks
- Mathan Games for making the homebrew game
- This video for showcasing a lot of neat homebrew games, which is how I learned of this game in particular
nymx: Claiming for judging.
nymx: Found 1342 frame improvement, via a glitch that I discovered. I'm dropping out for another judge to take on.
nymx: Found another 2385 frames and replaced the movie file.
nymx: Hopefully this is the last time. Studying the map of this game has been very rewarding. 1944 more frames have been cut...for a total of 5671 frames.
nymx: Ok...this is it. I'm not touching this again. I did one last run-through to confirm movement optimization and found 42 frames.
ThunderAxe31: The goal for full completion is clear, and the execution is very optimized. Accepting.
