Undertale Adventures X Tutorial: Beginner Guide to Units, Traits, and Codes

A complete Undertale Adventures X tutorial covering your first match, the four combat roles, trait rerolls, codes, and progression systems.

What Is Undertale Adventures X?

Undertale Adventures X is a free Roblox tower defense experience from Side Productions, the verified Roblox community that owns the game page. You defend a base against incoming monster waves using Undertale-inspired units, then level those units and strengthen them with traits between matches. This Undertale Adventures X tutorial walks through the opening loop, the four combat jobs your lineup needs, how trait rerolls actually work, and where codes and side systems fit into your progression.

If you are brand new, the important thing to understand is that this Undertale Adventures X tutorial is not about memorizing a single "best" unit. It is about spending a small opening purse wisely, upgrading with money earned from kills, and only gambling on traits once you can read the percentages on your own screen.

Quick facts

Detail	What we know
Developer	Side Productions (verified Roblox community)
Genre	Strategy / Tower Defense
Created	July 16, 2024
Server size	15 players
Entry cost	Free; optional Robux passes exist
Listing updated	October 12, 2026
Visits (community snapshot)	Roughly 17.4 million reads in mid-October 2026

One caution: that visit number comes from a public record read on October 13, 2026, and it moves constantly. Treat it as a snapshot, not a live counter.

Undertale Adventures X Tutorial: Surviving Your First Match

A match starts with the units you already own and a limited opening purse. The general shape of a first clear looks like this:

Step	Action	Why it matters
1	Place one unit that can actually hit the lane	An early placement that deals damage starts generating income
2	Bank kill money before upgrading	Upgrades scale better once you have a damage source already on the map
3	Add coverage for bosses and crowds	A single-role lineup stalls out around the mid waves
4	Upgrade the unit doing the most work	Concentrated investment beats spreading gold thin
5	Read the wave pattern before the final stretch	Knowing what is coming lets you place rather than panic
6	Finish the clear, then leave the match	Progression happens between matches, not during them

Most community lineups repeat the same advice: get something on the board fast, then let defeated enemies pay for the next step. The opening purse is intentionally tight, so your first placement decision matters more than any later one.

Between matches is where you actually grow

Once a clear is stable, the loop shifts. You summon or earn your next role, level the unit you plan to keep, and roll traits only after the trait screen shows you the percent. Codes, when they still work, go into the Codes button on the right side of the screen.

That order is not arbitrary. Leveling a unit raises a floor you can count on. Rolling traits is a gamble with a fixed rate table. Do the guaranteed upgrade first, then spend on the gamble.

The Four Combat Jobs Every Lineup Needs

Player experience consistently points to four jobs rather than four specific units. Fill each job and you can swap in substitutes as your roster grows.

Job	What it does	What happens if you skip it
Area damage	Clears groups of weaker enemies	Waves pile up faster than you can kill them
Boss damage	Bursts down single high-health targets	You stall on boss waves and lose the base
Front line	Holds a choke point and buys time	Enemies reach your damage units and end the run
Crowd control	Slows, stalls, or repositions enemies	Fast waves slip past your coverage gaps

Building around substitutes

Early on, you will not have a perfect unit for each job. That is fine. The goal is coverage, not perfection — a slightly weaker area-damage unit still does the job that an empty slot does not. As you unlock more Undertale-inspired units, upgrade the one filling your weakest role rather than chasing a new summon.

Traits Explained: Read the Percent Before You Reroll

Traits are the long-term power layer. A reroll assigns one of the twelve listed traits, and the outcome is weighted by a rate table. Community-reported odds screens from the game's earlier updates showed rates as low as 15% for a specific result like Royal Guard Soul, which tells you something important: rerolls are a resource, not a slot machine you pull for fun.

Trait concept	What it means for you
Reroll	Assigns one of twelve traits; the old result is replaced
Rate	Each trait has a listed chance, visible on the trait screen
Buff traits	Change how a unit performs, not just its raw numbers
Chase traits	Low-rate, high-impact results worth saving rerolls for

A November 29, 2024 community video described the Perseverance buff that the published rate table still shows. Whether current numbers match that table is something you should verify yourself — open your own Traits menu and read the percentage before you spend a large stack of rerolls.

When to reroll

Situation	Reroll?
You just got the unit and have not leveled it	No — level first
You have a handful of rerolls and one main carry	Yes, but only on that carry
You are rerolling a unit you rarely field	No
The trait screen shows a rate you have not read	No — read it first

Codes, Raids, the AFK Chamber, and the Underpass

Codes are the fastest early boost, but they expire. Community reports list 2KCCU! and FREESTUFF! as a working pair in earlier periods, with older strings archived as dead. Always type a code into the Codes button on the right side of the screen and check whether it was accepted before assuming it worked.

Code (community-reported)	Status	Notes
2KCCU!	Reported working in earlier periods	May have expired; verify in-game
FREESTUFF!	Reported working in earlier periods	May have expired; verify in-game
Older strings	Archived	Treat as expired

Beyond codes, three side systems open up once your clears are stable:

Raids tokens — a currency tied to raid content that you accumulate as you play.
AFK Chamber — passive progress while you are away from the keyboard.
The Underpass — a reward track that community footage from the Waterfall update showed as part of the progression path.

Community video published September 21, 2024 showed the Waterfall update as playable, including a new map, a Waterfall summon, the Underpass reward track, and a 25-wave anniversary raid that paid candles for gift skins. That footage is a player recording, not an official patch note, so treat the details as a snapshot of that era rather than a current changelog.

For the platform itself, you can find the game through the official Roblox platform, and the source franchise is documented at the official Undertale site.

Beginner Mistakes and a Progression Checklist

Most early losses come from a short list of habits. Here is how to avoid them.

Mistake	Fix
Spending the whole opening purse on one expensive unit	Place something cheap that hits, then upgrade
Ignoring bosses until they reach the base	Keep one single-target damage unit ready
Rerolling traits on an unleveled unit	Level first, trait second
Copying a tier list without checking your roster	Build for role coverage, not for names
Typing codes without checking if they were accepted	Confirm the reward before moving on
Never touching Raids, AFK, or the Underpass	Use them once clears are stable

A simple weekly routine

Clear one defense to keep your income and habits sharp.
Redeem any code you have not tried yet, and note the result.
Level the unit that carried your last clear.
Roll traits on that same unit only.
Bank one raid or Underpass session for later power spikes.

This Undertale Adventures X tutorial intentionally puts leveling ahead of trait rolling every time, because that is the order that produces steady progress instead of a reroll stack burned on a unit you will replace.

FAQ

Is Undertale Adventures X free to play? Yes. The listing shows no paid entry price, and optional Robux passes exist for players who want them. You can start the defense loop without spending anything.

Who develops Undertale Adventures X? Side Productions, the verified Roblox community linked directly from the game page. The experience was created on July 16, 2024, and its public record was updated on October 12, 2026.

How do codes work in this Undertale Adventures X tutorial? Open the Codes button on the right side of the screen and enter the string. Community reports list 2KCCU! and FREESTUFF! as previously working codes, but codes expire without notice — confirm the reward appeared before you count on it.

Do trait rates still match the old table? Trait rerolls assign one of twelve listed traits, and a published rate table matched an earlier odds screen showing Royal Guard Soul at 15%. Because rates can change between updates, read the percentage in your own Traits menu before committing a large stack of rerolls.

The best way to learn this game is to play one clear, then upgrade one unit, then read one trait screen. Follow that loop and the rest of the systems — Raids, the AFK Chamber, and the Underpass — will make sense when you get there.