Rabbit's All-Comers Mapping Project, or RAMP, is a Doom 1 & 2 mapping community project designed to let anyone submit a map, as long as it follows common decency rules. It is hosted by DavidxNewton.
There are very few restrictions; for all intents and purposes as long as it is in the UDMF format and runs in GZDoom (and doesn't replace anything or interfere with the rest of the project), etc etc. It sounds like a lot, but it's really not. However, a general rule is that you shouldn't start before June, and that your map shouldn't exceed 10 mins in length. Both of these are considered very soft rules, and likely won't get your project taken out, though the first one is the most heavily frowned upon should you break it.
During the month of June, you are allowed to create up to 3 maps, and submit them by June 30th.
So far, we have had 3 RAMPs, the most recent as of this writing being RAMP 2024. As you may expect, the others were RAMP 2023, 2022, and 2021.
I actually have entries for RAMP 2023 & 2024, being MAP147 (RECURSION) and MAP243 (Camp Soelil), respectively.
It's pretty easy to make a Doom map, actually! Every year, David does a video series where he shows newcomers how to make a map, and then plays through every single map in the project, devoting about 10 minutes to each.
There's also a discord that you can find through David's videos that I spend a lot of time in. The community surrounding the project is genuinely one of the nicest and most helpful I've been in, and doesn't really die off during the off season.
If you're interested, be sure to check it out this June!