Top 7 C++ multiplayer-game Projects

OpenJK

16 1,939 8.2 C++

Community effort to maintain and improve Jedi Academy (SP & MP) + Jedi Outcast (SP only) released by Raven Software

Project mention: Microsoft could cram more ads into Windows 11 – this time in the Settings app | Recent moves with the Start menu are now being echoed within the Settings panel in testing | /r/technology | 2023-05-08

openspades

6 1,099 2.9 C++

Compatible client of Ace of Spades 0.75

Project mention: Open source Diablo 1 engine – DevilutionX 1.5.0 released | news.ycombinator.com | 2023-06-17

Ace of Spades is one. I usually play with the OpenSpades client[1], but there is also Betterspades[2], and probably many other clients I don't know of yet. There are usually about 10-50 players online on the public servers listed on BuildAndShoot[3], variable depending on the time of day and mostly from Latin America it seems.
One can host the game with piqueserver[4]. I'm not sure if one can still host with the original Ace of Spades server, but the game was 'shut down' in 2019 so maybe not.
[1]: https://openspades.yvt.jp/
[2]: https://github.com/xtreme8000/BetterSpades
[3]: https://www.buildandshoot.com/servers/
[4]: https://www.piqueserver.org/

WorkOS

workos.com sponsored

The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.
Hypersomnia

5 902 9.8 C++

Multiplayer top-down shooter made from scratch in C++. Comes with an in-game Editor!

Project mention: My competitive top-down shooter brings open-source to eSports. Written from scratch, in bare C++ - runs natively on Linux. AppImage is just 30 MB. Coming to Steam on 28th. | /r/linux_gaming | 2023-12-11

Cool part? Part of the game's source code was used in Assassin's Creed: Valhalla, as well as Skydio drones. See our GitHub for details: https://github.com/TeamHypersomnia/Hypersomnia

open.mp

3 393 9.0 C++

Open Multiplayer, a multiplayer mod fully backwards compatible with SA-MP

Project mention: Is open.mp dead? | /r/samp | 2023-10-16

P.S. Im not trying some incredible debate here. Its just that I payed 60$ a month on hosted tabs since 2014, and Im trying to do the same type of advertisement but where should I advertise my server if open.mp is dead?

aws-gamelift-sample

1 233 0.0 C++

A simple full-stack game sample using GameLift and AWS services.
Commander_Wars

28 199 9.7 C++

The aim of this project is to create an Advance Wars Clone with a lot of additions customizations and modding support. For Contact Inforamtion see the wiki page. Take a view on the game.

Project mention: Xanari Crew Campaign Playthrough Part 1 - Custom Campaign for Commander Wars (AW Fangame) | /r/Advance_Wars | 2023-06-01

Commander Wars: https://github.com/Robosturm/Commander_Wars

SMN2

1 66 4.9 C++

Character Movement Network Prediction easily accessible in UE5 Blueprints!
InfluxDB

www.influxdata.com sponsored

Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020).