Encounter immunity on route transitions

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entrpntr
Pokémon Trainer
Posts: 141
Joined: Wed Feb 04, 2015 11:22 pm

Encounter immunity on route transitions

Post by entrpntr » Sun Jun 14, 2015 10:52 pm

In Gen 2, after battles (wild/trainer), you have 4 steps of immunity, which is commonly known.

Today, it was discovered that there are also 4 steps of immunity on route transitions. When arriving on a new route from a warp point (e.g. Ilex Forest, caves, ladders), you can take the full 4 steps and be guaranteed of no encounters. When simply crossing a boundary (e.g. Olivine water <-> Route 40 water) or being pushed a tile when exiting a cave/door, the game decrements the step counter, so you only have 3 additional steps of immunity.

There are turnframes in Gen 2 which can eat into these step counters (including after battles), but I don't have a full understanding of them yet. Turnframes occur from non-moving states if you don't continue in the direction you are facing, as well as on sidebonks from a moving state. They occur after battles, picking up items (e.g. Route 32 Super Potion), menuing, or manually stopping (**EDIT: this includes bonking and turning in place). They don't have the unintuitive Gen 1 mechanics of occurring after the "first turn" while in a moving state.

Apart from generally taking movement patterns that avoid potential turnframes from encounters (e.g. Route 30 to/from Mr. Pokemon & Union Cave), the biggest application I can immediately see is the Ice Path in Gold. Before we would always Super Repel immediately after entering the Ice Path and need perfect movement in order to get 2 Super Repels to last through the cave. Now the best play is presumably to Super Repel after 4 steps, which gives some margin for error (and also makes it easier to avoid bonking on the first rock).

Thanks to Sinstar for helping me test and Mountebank for looking into game memory to confirm these mechanics.

**EDIT (28 Aug 2015): You can do a RAM watch on D179 (Gold/Silver) or D452 (Crystal) if you want to see what is going on for yourself. The counter starts at 5, but you can get an encounter on the step it goes down to 0.

More information on turnframes in this thread: viewtopic.php?f=7&t=489.

entrpntr
Pokémon Trainer
Posts: 141
Joined: Wed Feb 04, 2015 11:22 pm

Re: Encounter immunity on route transitions

Post by entrpntr » Thu Sep 17, 2015 3:33 am

One more application that came to me while daydreaming is the Rock Tunnel repels. Instead of walking into Hiker Jim's vision, you can talk to him, then Super Repel after 4 steps in Rock Tunnel. The first Super Repel wears off 2 tiles into Rock Tunnel, so this came up 1 tile short before encounter immunity was fully understood.

It looks like this: https://dl.dropboxusercontent.com/u/460 ... rPlant.mp4. This saves about 0.75 seconds (46 frames I believe) over the previous best known movement.

There's only 1 tile to spare on the repels so it requires perfect Rock Tunnel movement (previous movement could waste up to 6 tiles), but this is reasonably easy to execute in practice. I enter the ladder on the 3rd floor from the bottom (moving 2 tiles to the left is an easily acquired feel) and the ladder on the 4th floor from the left (trickier; my cue has been to flick up quickly after 4 back & forth bike animations then try again if I bonked).

Though easy in practice, it admittedly is different from doing it cold in a run (on the plus side, it is immaterial if you screw up movement prior to Rock Tunnel since you still get your 4 free encounter-immune tiles). Either way, figured I'd point it out. I'd stick to repelling at the first cut tree or throwing in a Max Repel if you want to avoid the stress of the tight movement constraints, but both of these are well over a second slower optimally due to the extra menu / extra scrolling.

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