Before we even think about our mod we need to get the tools required to make it. You can download this tools on the modding wiki linked right here.[tein-modding.wikia.com]
Once you've clicked on the link the modding wiki page will show up and these 4 softwares will be up for download on the wiki:Even though there are 4 tools here you'll only need 2, of which being the Level Editor and the Helper.
The level editor is quite self explanatory. It's what you need for building the level. The helper is to get around much faster, for example if you've built you're entrance in the Hollows 3 then you can use the helper to instantly teleport there. Once you've downloaded these 2 tools I suggest making a folder named TEIN Modding Kit in your desktop, it's a very efficient way of keeping your mods and your mod making tools organized. Now once you've downloaded the tools and made the folder go to the Level editor you've previously downloaded. At the top of the editor you should see and icon that looks like this named gpak unpack: if you click on this it will open up your file explorer. Go to this and once you have click on game.gpak. (NOTE: to make this process faster and easier create a desktop shortcut for this). Once you've unpacked game.gpak it should come up with a folder in the file we got it from simply named game. To avoid this folder clashing with anything else in theendishnigh folder, rename it to whatever you like. I renamed mine "game[modfolder]". Now create 2 folders one named "tilemaps" and the other named "data". Make sure there uncapatalized it is crucial! If you would like custom music make 2 more files one named "audio" and the other one named "music" and put the music folder in the audio folder. Like the others make sure it is uncapatalized. Now, we can leave the tilemaps folder, the music folder and the audio folder to one side. Go to the unpacked and renamed "game" folder and go to the data folder in there. In the data folder you will see these files: copy the "map.csv" file the "levelinfo" file and the "tilesets" file into the uncapatalized data folder in your "theendisnigh" folder. If you've followed these steps correctly you're "theendisnigh" folder should look like this:

Now that you've got the tools made all the folders and unpacking the gpak, open up the level edtior once again and on the top there should be an icon that looks like this: once again upon clicking it it should open up your file explorer, however this time open up to: it should show up every level/screen in the game. Something odd about how the levels are set is that level 1 (except from the end) will be called (world number) - 0 and for example arid flats 1, will be 2-0. For this example I will use the end 1. Once you have made the editted version while saving the file make sure you a) keep the level name the same and b) DO NOT save it in the tilemaps folder you got the level from instead save it into the uncapatalized tilemaps folder we've made in "theendisnigh" folder. My editted version looks like this:
As you can probably tell you MUST have these level transition tags. that looks like this


Using the scroller on your mouse you can change the direction it points at. As a beginner don't use the diagonal ones yet because it might come across as confusing. Now that you've added the world entrance you can create the first level of your world. The minimum size is 54x32 you can use the camera tags to make the screen more zoomed in. (Put it on all 4 edges of where you'll like the camera to zoom in on. when you make a new map it is essential you put a debug spawn tag which looks like this:


and my map looks like this:


save it to yet again where you saved your edited entrance and keep to the format its named in so (world number) - level number. My world is called "The Acsension" so mine will be called a-0. Your mod can be called (world)-1 mine is -0 because its an entrance that requires 3 keys. Now if you open the end is nigh and went to the area you editted the changes will be there, however if you try to enter your world it will come up with this error:


This is because it isn't registered as a map on the "map.csv file" in our data folder we've talked about earlier. Assuming you have a google account go to google drive and upload the "map.csv" file we've previously mentioned. Link to google drive [drive.google.com] once you've done this go to google spreadsheets - Link to google spreadsheets[docs.google.com]. Now open the map.csv file in google spreadsheets. and find what level you made the entrance at. Since my entrance is at the end 1 mine will be 1-1 once you found it write the level name wherever the entrance for it is for example mine is under 1-1 so I'll write mine there if yours was hollows 3 to the left you'd put it to the left of hollows 3. When you write it in make sure it is called the same as what you named it in tilemaps and make sure you put the .lvl on the end. Mine will look like this:


Now save the map.csv file and overwrite the current one in our data folder in "theendisnigh" folder, and when you open the game and go to the entrance is should work this time.


Now if you've done it like I have it should be working however it wont have a name it wont have music and it'll be very bland. It doesn't have a name because we need to edit it into the "levelinfo" file. So as usual open up to and click on levelinfo. Now because this is a custom level the ID should be -1. so type in For some reason the game is write with # instead of // to make it a comment. Now, obviously it wont be exactly that it will be filled in with what your information is. So for example mine will be Now if you load up the game it will crash whenever you go into the level and this is because we need a tileset for the name to show up. This isn't covered in this guide because I don't know how to do it but you can create custom tilesets. But because we don't know how to do this we'll copy a tileset from the game. So go to and go to tilesets. For this example I'm gonna use the tileset for the hollows. So I'm going to do "ctrl+f" and search "hollows" or what world you'll like the tileset to be. When we did the level name mine was "a-0" when you copy whatever tileset there will be a number, possibly a number and a letter and then a bunch of code in brackets. Change that number/letter what whatever number/letter was at the front of your level name. So since mine was "a-0" the digit will be "a" then a bunch of code in brackets. Now if you've done this correctly you should have music you're world will look like whatever vanilla tileset you copied from and it wont look bland. Now theres only 2 issues. a) the area name is the same as the one you copied from and b) the area names label shows up. Now since this is a mod we can't add the label unless you have a certain software which I don't have so we won't cover it in this guide. So to fix this a) change the name from whatever world it is to yours so mine will change from "The Hollows" to "The Ascension" and change the "area_label_frame" to 0. Now everything should be fixed and mine looks like this:


If yours is very dark like mine then you can change the "shader_param" in the tileset file to fit your likings.

Custom music is probably the most tedious thing we'll be covering in the guide so we're going to make it have its own section. Now if you want you can keep your tilesets music for example my music will be the same as the Hollows. But if you don't want to import custom music but still want to change it then just ctrl+f search for whatever vanilla song you want and go to your tileset and change the music to that musics. You'll change the line to change the music. That line is also the line of code you'll copy from a different tileset to get the custom music. in the past example mine will be the hollows music but if you didn't use the hollows it'll be different but it'll still say music[blahblah,blahblah] then ambience blah blah. Now moving on to the confusing part adding custom music. Now to do this you'll need audacity which can be downloaded here[www.audacityteam.org]. Now your song can be anything. It can be dubstep it can be heavy metal. But I personally like to do rock covers of classical music because it's the same thing that the vanilla games music did. Im using this.Then change it ro mp3 using an mp3 converter[www.onlinevideoconverter.com]. Now open the mp3 into audacity and make 2 seperate tracks one track will be before the "beat drops" and the other one will. Now to export mp3 files from audacity you need something called "lame"". Which you can get from here[lame.buanzo.org] (NOTE: When downloading lame there are alot of ads on the page so make sure you click the correct link). Once you have "lame" you can export the 2 mp3 files and name them "something_intro" and "something_loop" and put then in you music file thats in the audio file that we made earlier. Now if you haven't noticed yet The End is Nigh uses a file format for music called ".ogg" so you need to convert those .mp3 files into .ogg files which can be done here here[audio.online-convert.com]. Now replace the .mp3 files with the .ogg files and you're set. Now theres only 1 last thing we need to do when you go to the "music" line of code add the name of your "intro and loop" .ogg files. For example mine is " Ta-daa Now you have custom music, your own world and an entrance to your world!

Welp now that you've made your first level all you have to do is keep making more levels and then write the level in "levelinfo" by simply copying the first line we did but changing the name of it. And also make the level on the map.csv file. I reccomend just planning everything out first on the map.csv file so you dont need to keep going back to it after every level. To add mods you simply have to put all the files the mods download comes in on your "theendisnigh" file but don't forget when you've finished with your mode just leave the mod area to a main game area so when you change the mod you don't need to change it back leave and change it to the one you want to play. I suggest creating a mods folder to keep all your mods in check. Now lastly my suggestions for mods to play is (if you're well skilled at the game) axonic collapse, city of tethys and remorse. If you're not that great at the game I suggest the flashback pack. All mods suggested as well as all the other mods and their downloads can be found on this google sheets file[docs.google.com] as well as the TEIN discord[discord.gg] which has other modders and people to help you with modding. Good luck modding and if you have any questions feel free to ask in the comments.