Undertale is Toby Fox's 2015 role playing game about a child who falls into the Underground and has to find a way out. Its hook is that every encounter can be ended without killing: you dodge patterned attacks inside a small box, then use ACT and MERCY instead of FIGHT. A single run takes roughly six to seven hours, and the game quietly records what you chose to do along the way.
These tips go beyond the basics. They're the strategies experienced players use to play more efficiently, the hidden mechanics most people miss, and the optimizations that compound over a full playthrough. If you're just starting, check our beginner's guide first.
Essential Tips
1. Use Check on every new enemy before anything else
Use Check on every new enemy before anything else. The flavour text points at the ACT option that will spare it, and it costs one turn you were going to spend dodging anyway.
2. Toriel's phone number is not decoration
Toriel's phone number is not decoration. Calling her from different rooms produces different lines, and in the Ruins the phone is part of how the area is meant to be played rather than an optional extra.
3. Buy at least one Spider Donut or Spider Cider from the bake sale in the Ruins
Buy at least one Spider Donut or Spider Cider from the bake sale in the Ruins. Muffet in Hotland checks whether you supported the spiders and behaves very differently if you did.
4. Temmie Armor lists at 9999G, more gold than a normal run produces
Temmie Armor lists at 9999G, more gold than a normal run produces. Talk to the Temmie asking for college money and pay repeatedly until the price falls to 1000G, at which point 20 defence carries you through almost anything.
5. Sparing is often a sequence, not a single action
Sparing is often a sequence, not a single action. Some enemies need several ACT commands in order and some need their partner spared first, which is why the dog family in Snowdin catches new players out.
6. Green SOUL mode in the Undyne fight removes your ability to move at all
Green SOUL mode in the Undyne fight removes your ability to move at all. You hold a directional shield instead, so read the direction each spear comes from and face it rather than trying to dodge sideways.
7. Yellow SOUL mode inverts the game during Mettaton encounters and lets you shoot upward
Yellow SOUL mode inverts the game during Mettaton encounters and lets you shoot upward. Keep firing between dodges, because both damage and the on screen ratings depend on how much you put out.
8. Every save point is also a full heal, and one sits before each major fight
Every save point is also a full heal, and one sits before each major fight. If you walk into a boss on damaged HP, you walked past a save point.
9. The True Pacifist ending requires zero kills across the entire run, not just the closing chapters
The True Pacifist ending requires zero kills across the entire run, not just the closing chapters. One accidental kill in the Ruins blocks it until you finish a neutral ending and go back through.
10. The Genocide route is a grind rather than a rush
The Genocide route is a grind rather than a rush. Each area has to be emptied until random encounters stop spawning, and two of its fights are far harder than anything on the other routes.
Advanced Strategies
Build Optimization
The difference between an average build and an optimized one is massive. See our builds guide for full breakdowns.
For Neutral Route (A-Tier):
- Focus on Bullet dodging in the SOUL box combinations for maximum output.
- Core gear: Stick
- Stat priority: Offensive stats first
For True Pacifist Route (A-Tier):
- Versatile approach that handles any situation.
- Core gear: Toy Knife
- Stat priority: Balanced stats
Mechanic Interactions
Understanding how Undertale's systems interact is where the real optimization lives. Our combat guide covers this in detail.
Bullet dodging in the SOUL box + FIGHT, ACT, ITEM and MERCY: On an enemy turn your SOUL becomes a small red heart inside a rectangular box and you dodge projectile patterns with the arrow keys. Combined with FIGHT, ACT, ITEM and MERCY, fight uses a timed bar where stopping the cursor dead centre deals maximum damage.
LOVE, EXP and LV + Coloured SOUL modes: EXP stands for Execution Points and LV stands for LOVE, and both rise only when you kill. When paired with Coloured SOUL modes, several bosses recolour your soul and change the rules entirely.
Route tracking across a whole run scaling: The game counts kills, spares, deaths and dialogue choices, and it holds those counts across saves. Which of the three main endings you reach depends on what those counters say when you get to the end.
Equipment Efficiency
| Equipment | Best Use Case | Why |
|---|---|---|
| Stick | LV1 runs and anyone intending to spare every monster in the game. | The starting weapon at 0 attack, found in the Ruins. |
| Toy Knife | Early neutral runs where Froggits and Whimsuns take too many turns to clear. | 3 attack, found in the Ruins. |
| Worn Dagger | The final stretch of a neutral run. | 15 attack, found in New Home near the end of the game alongside the Heart Locket. |
| Burnt Pan | Runs built on stacked healing food rather than raw damage output. | 10 attack, found in Hotland. |
| Real Knife | Genocide runs, where it removes almost every encounter in a single hit. | 99 attack, and it only exists on the Genocide route. |
Location Efficiency
The Ruins (Opening 45 to 60 minutes): The opening area, a purple stone maze of switch and rock puzzles under Toriel's care. It teaches ACT through Froggits and Whimsuns, hides the Toy Knife and Faded Ribbon, and closes with the game's first real boss fight.
Snowdin (Roughly one to two hours in): A snowfield and town run by Papyrus and Sans, with a run of deliberately silly puzzles, a set of dog themed enemies and a shop stocking the Tough Glove and Manly Bandanna. It is the most forgiving stretch of the game.
Waterfall (Roughly two to four hours in): Dark caverns of glowing crystals and echo flowers, with Undyne hunting you across bridges and reed beds. Gerson's shop sits here, and Temmie Village hides off the main path.
Hotland (Roughly four to five hours in): Lava, conveyor belts and Alphys's laboratory, plus a string of Mettaton set pieces that use the yellow SOUL shooting mode. Bratty and Catty run a stall outside the MTT Resort.
The CORE (Roughly five to six hours in): The Underground's power plant, a blue and grey maze whose layout shifts depending on choices you made earlier. It is the last area before New Home and the shortest of the major zones.
Mistakes Even Veterans Make
- Killing a handful of monsters early and then aiming for True Pacifist. Any kill at all blocks it for that run.
- Spamming FIGHT on Toriel because the ACT options look like they are doing nothing. Sparing her takes many attempts and the game expects persistence.
- Walking past every shop and reaching the endgame with three items and no armour.
- Selling the Butterscotch Pie for gold. It heals 64 HP and has a specific extra effect in one late fight.
- Sampling the Genocide route out of curiosity and assuming a reload undoes it. The game keeps records across saves.
Pro Quick Tips
- Use Check on every new enemy before anything else. The flavour text points at the ACT option that will spare it, and it costs one turn you were going to spend dodging anyway.
- Toriel's phone number is not decoration. Calling her from different rooms produces different lines, and in the Ruins the phone is part of how the area is meant to be played rather than an optional extra.
- Buy at least one Spider Donut or Spider Cider from the bake sale in the Ruins. Muffet in Hotland checks whether you supported the spiders and behaves very differently if you did.
- Start with True Pacifist Route, switch to Neutral Route when ready
- Invest in Stick above everything else
- Clear areas in order: The Ruins → Snowdin → Waterfall → Hotland → The CORE. See our maps guide
- Bullet dodging in the SOUL box + FIGHT, ACT, ITEM and MERCY together are stronger than either alone
More Undertale Guides
- Undertale Undertale Overview
- Undertale Best Builds
- Undertale Tier List
- Undertale Walkthrough
- Undertale Beginner's Guide
- Undertale Weapons Guide
- Undertale Combat Guide
- Undertale Boss Guide
- Undertale Maps & Locations
- Undertale Crafting Guide
- Undertale Classes & Characters
Similar Games
If you enjoy Undertale, check out these related guides:
- Elden Ring Tips & Tricks: rpg game with similar mechanics
- Baldur's Gate 3 Tips & Tricks: rpg game with similar mechanics
- Cyberpunk 2077 Tips & Tricks: rpg game with similar mechanics
