Working docker container not being marked as successful deployment by App platform

I want to play the original Doom online with a friend. For this purpose, I have created a dockerfile that starts up a server, and I want to deploy it as a Digital Ocean app. However, the command that starts the Doom server is somehow preventing Digital Ocean’s platform from seeing that the deployment was successful. See this screenshot of my deployment logs:

https://ibb.co/cbKcfHs

The bottom line, MAP 01: entryway , means that the server is running, and waiting for connections on its port. However, this server program is running in the “foreground”, it doesn’t offer a detached mode, and adding & to the command to force it to run in the background doesn’t seem to work either. Since the server program technically doesn’t end until you press ctrl+c, Digital Ocean’s app platform can’t see it’s finished, and the deployment times out.

How do I make the app platform recognize that the deployment was successful?

Edit: My dockerfile is below. This runs perfect on my own machine, with the command docker run -d -p 10666-10700:10666-10700/udp doomserver

FROM ubuntu:20.04

ENV TERM linux
ENV DEBIAN_FRONTEND noninteractive

RUN apt-get update
RUN apt-get install --no-install-recommends -y  
RUN apt-get install --no-install-recommends  wget -y
RUN apt-get install --no-install-recommends  -y gnupg2 
RUN apt-get install --no-install-recommends  software-properties-common -y
RUN mkdir ~/.zandronum

RUN wget -O - http://debian.drdteam.org/drdteam.gpg | apt-key add -
RUN add-apt-repository 'deb http://debian.drdteam.org/ stable multiverse'
RUN apt-get install zandronum doomseeker-zandronum -y 

RUN apt remove wget -y
RUN apt remove gnupg2 -y
RUN apt remove software-properties-common -y

COPY DOOM2.WAD /usr/games/zandronum/DOOM2.WAD
COPY brutalv21.pk3 /usr/games/zandronum/brutalv21.pk3 

RUN apt-get -y install sudo
RUN useradd -m docker && echo "docker:docker" | chpasswd && adduser docker sudo
USER docker

# CMD ["/bin/bash"]
EXPOSE 10666-10700/udp
ENTRYPOINT ["/usr/games/zandronum/zandronum-server", "-port", "10666", "-iwad", "/usr/games/zandronum/DOOM2.WAD", "-file", "/usr/games/zandronum/brutalv21.pk3", "+sv_hostname", "\"Welcome to AH FREE KA\"", "&"]