The way this works is explained more thoroughly at How to Solve the Snake Reflection Tunnel Puzzle. Here's the version with more text from game and less strategy advice.
The minigame begins:
You glance behind your reflection. The serpent seems to be heading <direction>.
Directions are left, right, up, or down.
Each stage of the game, no matter what, you can choose from any of these options:
- Run left
- Charge right
- Clamber up
- Find a way down
- Stand your ground
All subsequent stages have information displayed in the following order. Exact text in sections below.
Snake Movement
Snake Attack
Reward
Snake Hint
Snake Movement
If the snake doesn't change direction from the previous Snake Hint:
The serpent sways and heads <direction>.
If the snake turns from the previous Snake Hint:
The serpent heads <direction> but sways at the last moment and heads <orthogonal direction> instead.
If the snake reverses direction from the previous Snake Hint:
The serpent heads <direction> but it was just a feint. It coils and lunges <opposite direction> instead.
If round x Snake Hint = round x+1 Snake Movement = round x+1 Snake Hint = round x+2 Snake Movement (calculated in advance), then round x+1 movement is replaced by the Metros message:
The serpent lunges <direction>, coiling through the tunnels at a reckless speed. The mirror shakes like a Metros train is passing right beneath your feet.
Snake Attack
If you dodge, meaning the direction you ran is opposite direction from Snake Movement, or one direction clockwise from Snake Movement:
It tries to nip at you as it passes, but you're already too far away. It has to loop back around and come after you from another angle.
If you narrowly miss, meaning the direction you ran is one direction counterclockwise from Snake Movement:
It nips at you as it passes, dealing <?–15–?> damage, but has to loop around and come after you from another angle. You feel yourself slowing down, though, as the poison courses through your veins… your reflection's veins?
Gain 5 duration Serpent Venom
Needs message and result if this beats you to hell.
If you narrowly miss while you already have Serpent Venom:
It catches up with your reflection, slowed by the dose of venom already coursing through its veins. Your world goes dark as the serpent's jaws close around your reflection.
You take <all hp> damage.
You're pretty beaten up. You can't make it any further without resting.
Ends encounter.
If you run in the same direction as Snake Movement:
Unfortunately, that's exactly where your reflection was running. Your world goes dark as the serpent's jaws close around your reflection.
You take (all hp) damage.
You're pretty beaten up. You can't make it any further without resting.
Ends encounter
If you dodge the Metros message:
On the bright side, it whizzes right past your reflection. Score!
plus first time per day?:
In the distance, you can see an apple tree swaying violently, hurling its fruit in every direction. Well, at least it's not just your mirror and windows shaking so hard they sound like they're going to break… more.
Changes next Leafy Tree apple picking result.
If you narrowly miss? the Metros message with Serpent Venom:
With the poison coursing through its veins, your reflection just can't hope to outdistance the serpent.
Thankfully, it charges entirely past your reflection, but its whip-like tail opens a bleeding wound in your reflection's back… gah, and yours as well, for <all hp?> damage.
You've earned 2 XP in Perception
Ends encounter
If you stand your ground:
You stand your ground against the charging serpent. It bites your reflection and you can feel the poison coursing through your veins. Then it swallows your reflection whole and your world goes dark.
You take <all hp> damage.
You're pretty beaten up. You can't make it any further without resting.
Ends encounter
Reward
After stage 7?, sometimes?, once per day:
A piece of glass falls from your mirror. Hmmmm, hopefully that wasn't important.
You found: empty shard
After stage 13?, sometimes?, once per day, after first message:
Another piece of glass falls from your mirror, spinning across the floor. Thankfully they don't seem to be load-bearing.
You found: empty shard
After stage 25, first time per day:
A torrent of pieces fall from your mirror, scattering over the floor. Your reflection, the snake, the forest, the pond, and even the tunnels you're running through vanish in the deluge.
You found: empty shard
You found 4-5 shards: reflecting apples, reflecting scales, reflecting fish
You've earned 5 XP in Perception
Ends encounter.
Snake Hint
You glance behind your reflection. The serpent seems to be heading <direction>.
Or, later, depending on your buffed Perception:
The serpent's close now. It's hard to tell where it might be going with it so close to your reflection, but you see the serpent is slithering mostly <up and left / up and right / down and left / down and right>.
or
The serpent's close now. It's hard to tell where it might be going with it so close to your reflection, but you see the serpent is slithering straight down the middle… could be headed up or down, it's hard to say.
or
The serpent's close now. It's hard to tell where it might be going with it so close to your reflection, but you see the serpent is slithering side to side. It could just as easily go right or left.
Or, later still, depending on your buffed Perception:
The serpent's too close to your reflection to pick out where it might be going.