Introduction (also known as Survey) is the beginning of Chapter 1 of Deltarune. During this segment, the window title is "CONTACT" on the PC version.
The customization starts with the building of a body (also called a "vessel"). The first choice is the HEAD which has 8 options, the BODY with 6 options and the LEGS with 5 options.
These questions are meant to give the vessel a personality:
- What is its favorite food?
- Your favorite blood type?
- What color does it like most?
- Please give it a gift.
- How do you feel about your creation? (It will not hear.)
At the end of the questionnaire, the player is asked if they answered honestly, then asked if they have acknowledged the possibility of pain and seizure. The player names the vessel and then enters their own name using only uppercase letters.
Setting certain names for the vessel or creator alters the voice's response.
- By default, the voice says WE CALLED IT "<Name>." when naming the vessel and "<Name>". EXCELLENT. TRULY EXCELLENT. when naming the creator.
- If the vessel or creator name is set to "GASTER", the game returns to the Chapter select screen as soon as the last letter is typed.
- If the name is set to either "BERDLY," "CATTI," "JOCKINGTON," "RUDY," "ASRIEL," "TORIEL," "ASGORE," "ALPHYS," "UNDYNE," "BRATTY," "CATTY," "SANS," "GERSON," "QC," or "PAPYRUS,"  the voice says "<Name>." AN INTERESTING COINCIDENCE. when naming the vessel and "<Name>." HOW INTERESTING. when naming the creator.
- If the name is set to "KRIS", "SUSIE," or "NOELLE," the voice says "<Name>." AN INTERESTING COINCIDENCE. when naming the vessel and "<Name>." YOU ARE ABOUT TO MEET SOMEONE VERY, VERY WONDERFUL. when naming the creator.
- If the creator is named the same as the vessel, the voice says OF COURSE OF COURSE. OF COURSE THEY ARE THE SAME.
After this, the vessel is discarded as the screen goes black and the game states "No one can choose who they are in this world. Your name is..." The game then finally starts with Toriel yelling "KRIS!" with the player controlling said character.
In Chapter 2, the creator's name is used in the name of Castle Town. When starting a Chapter 2 save file without continuing from Chapter 1 completion data, the player is prompted to enter their own name (so that it can be used in the town's name), but is not given the opportunity to enter any information about a vessel. In the game data, the vessel defaults to the first option of each question, except for its gift, which defaults to Mind.
- Despite to the legs appearing similar, the fifth legs option is flipped horizontally.
- The "favorite food" question consists of non-food answers. Instead, each answer correlates to a sense:
- Sweet, Sour, and Salty are taste-related flavors.
- Soft, Pain, and Cold are associated with touching.
- One of the questions asks the favorite blood type of the Vessel, listing "A," "B," "AB," "C," and "D." Both "C" and "D" are blood types that do not exist in real life, and existing blood type "O" goes completely unmentioned.
- The names that cause the "INTERESTING COINCIDENCE" response are characters met in Hometown.
- Names of characters who only appear in Undertale but are mentioned or referenced do not cause a special response. Papyrus is exempt, as he is alluded to.
- After the vessel is discarded, every save file appears with the creator's name on the save.
- The character limit when naming the vessel is 9 (eg. DELTARUNE) whereas the character limit when naming the creator is 12 (eg. WINDINGASTER).
- The introduction music, ANOTHER HIM, resembles the track "Giygas' Intimidation" from EarthBound.
- In the original Chapter 1 Demo, if the vessel's name was set to "GASTER," the game would return to the beginning of the intro upon typing the last letter. If the creator's name was set to "GASTER," the game would shut down upon typing the last letter.