I’ve been looking around to try and figure this out, but i can’t find the information anywhere because every guide out there gives a description on how to add mods in the steam version. I have tried manually adding a mods folder, and sticking mods in it as i (as far as i know) am supposed to, but it still does not show up on the mods thing in-game.
What do i do?
Go to your install folders and you will see a folder called ‘‘mods’’ in there. Put the (most of the time) extracted ZIP in there, the folder you got from it, and then start up Game Dev Tycoon. Go to the Mods tab in the menu and select the mod, restart Game Dev Tycoon and you’re ready to go! 
There’s no folder named “mods” in it…
My Computer- Local C: - Program Files - GameDev Tycoon - mod folder.
I don’t know which OS you’re using so it might be in "Program Files (x86)
If there isn’t a mod folder in there, I believe you can just create one and download API, Ultimate Lib and then any mods you want…
Link for API - Official Modding F.A.Q
What do i do with the API?
Once you have a mod folder, you just un-zip and drop the gdtAPI folder in there and you’re done!
Then you just do the same for Ultimate Lib and all the mods you want.
Once you have them all in there, open up GDT, go to the pause menu, click on the “Mods” button which should be there by then, click on mod-API, UltimateLib, and the mods you want enabled.
Afterwards, close GDT, wait a second or 2, then re-open. All the mods you selected should be activated…
Also note, a lot of mods have issues with working on pre-saved games. You might want to start a new game just so you don’t get any errors.
Done what you said… mods don’t seem to show up though… Is there a file within the API-master folder or something, or am i doing anything else wrong?
I’m using Windows 8 by the way.
I don’t think you’re doing anything wrong… Here’s how my folder looks…
what does your initial game dev tycoon folder look like? my mods folder looks the same and it still isn’t working, i’m guessing i may be looking at the wrong place.
hm… Let’s see what @Charlie and/or @alphabit can say about this matter… I’m a bit clueless now…
Here’s my layout
Whooaaaa, your file has way more stuff in it than mine, sooo, does that mean im looking in the wrong place?
Alright, i was looking in the wrong spot. Found the right folder and got mods working! thank you for the help!
No problem!
Is that Windows XP? 
what you laughing at.
windows xp da best operating system.
da best os.
da best.
best.
What did you do i looked everywhere?!
don’t necro :[
for