Mega Man 7 Rush Search mechanics

Understandably, Rush Search is not a terribly popular upgrade in Mega Man 7, but it is of moderate importance for speedrunning now that I found the Wily Machine quick kill. In an attempt to figure out the odds of the trick working, and whether or not it is a worthwhile trick to attempt, I decided to dig into the code to figure out how Rush Search works.

When Rush Search is used in a location where there isn’t a fixed search (all known fixed searches are listed at the bottom of the MM7 item StrategyWiki page), the game will pull the lower RNG byte to tell Rush what he found. The RNG in this game changes wildly on every frame, and the function returns all values approximately equally. In short, it cannot be manipulated and isn’t skewed towards certain search results.

Rush search results

All possible Rush Search results, their probabilities, and the number of times I have found each item are listed in the table below. Small and large bolts are grouped together because the collection sound is the same for each and we don’t track bolt count in speedruns; there is no way to determine which drop it was.  Small and large ammo are grouped because Rush Search is only missing 2 ammo here, and either drop is sufficient to fill it.

These items are loosely separated into three groups: item that can be collected and grant control during cutscenes, items that can be collected but don’t grant control, and items that cannot be collected. Results in the first group are required for the Wily Machine quick kill.

Sprite Item Probability PJ’s total Class probability
small health Small health 24/256 (9.38%) 0 64/256 (25.00%)
large health Large health 8/256 (3.13%) 1
small ammo Small ammo 24/256 (9.38%) 2
large ammo Large ammo 8/256 (3.13%)
small bolt Small bolt 24/256 (9.38%) 2 50/256 (19.53%)
large bolt Large bolt 8/256 (3.13%)
extra life Extra life 8/256 (3.13%) 1
E tank E tank 4/256 (1.56%) 0
W tank W tank 4/256 (1.56%) 0
S tank S tank 2/256 (0.78%) 2
boot Boot 22/256 (8.59%) 6 141/256 (55.08%)
beer Can of beer 8/256 (3.13%) 0
glasses Broken glasses 8/256 (3.13%) 0
teeth Teeth 8/256 (3.13%) 1
bone Bone 8/256 (3.13%) 3
banana Banana peel 8/256 (3.13%) 0
watch Watch 8/256 (3.13%) 1
fishbone Fishbone 8/256 (3.13%) 2
tea kettle Tea kettle 8/256 (3.13%) 1
doll Doll 8/256 (3.13%) 1
little robot Little robot 8/256 (3.13%) 1
apple core Apple core 8/256 (3.13%) 1
tuna Can of tuna 15/256 (5.86%) 1
gameboy Gameboy 1/256 (0.39%) 0
chips Bag of chips 8/256 (3.13%) 2
bomb Bomb 7/256 (2.73%) 3

Total chances at Wily Machine quick kill: 3/31

Successes: 1