Free Games: Open Arena and Nexuiz

By Shamus Posted Friday Nov 9, 2007

Filed under: Game Reviews 24 comments

In last week’s post on Unreal Tournament vs. Quake ]I[ Arena, a couple of readers provided links to some games based on the Quake ]I[ Arena source code.

Id Software is in the habit of releasing the source code for their games under the GPL once the game has finished its run. It is one of many reasons I love and admire the company, even at times when I might be lukewarm to their games. They are a great bunch and have done a lot to enrich the medium as well as the fans. In 2005 they released the source to Quake 3 Arena, and since then I’m sure thousands have downloaded and experimented with the source. Of course, only a small percent of those projects ever see public release. Below are a couple that have made it far enough to make a worthy release and build a fanbase.

(I experimented with the source for the original Quake back in 2001, and what I remember most is that John Carmack is a very readable coder. When I had trouble understanding his code, it was because he was doing something clever or complex, not because the code itself was hard to follow. I can promise you this is not usually the case when dealing with source code. Making your code readable and easy to follow is extra work and requires dicipline, and I really appreciate the effort he puts into his work.)

The thing about releasing the games this way is that they do not give away the art assets, only the source. This means you have everything you need to build your own version of the Quake executable, but you have no maps, textures, sound effects, music, movies, player models, weapons, or interface graphics. That stuff is all copyrighted. If you want to make your own version of the game, you need to come up with all of that stuff yourself. This is a tall order, and I admire any group of enthusists that can come together and create a game like this.

I’m sure there are other projects out there, but Open Arena and Nexuiz are the ones that were brought to my attention and therefore the games that I played.

Open Arena

Reader Saborlas provided a link to Open Arena. It looks to be a fairly faithful reproduction of the original Q3A gameplay. The game mechanics remain largely unchanged, right down to the things the announcer says and the feedback sound when you tag a foe with weapons fire. Even the interface is the same, except with new art. Playing this game feels just like Quake to me, although someone with more time invested with the original might find differences I couldn’t detect.

It supports play against bots, although the AI seemed a little strange. The bots tended to stick to a very predictable circut, and would often run along in close proximity to other foes without fighting. Since the game is using the perfectly serviceble AI from Q3A, I’m assuming this must be a problem with the design of the level.

In any case, it is by no means complete. There are only a handful of maps, but what is there is solid and interesting.


Dihydrogen linked to Nexuiz, which is older (the project has been going for a couple of years now) and seems to have a different thrust. They aren’t making an exact copy of Q3A, but instead are trying to create something along the same lines but with different gameplay. The weapons, sounds, and interface are all very different.

I wasn’t able to give the game an honest evaluation. The mouse settings wouldn’t let me turn the sensitivity up high enough for the game to feel right. Even with it maxed out, turning my character still felt like piloting a barge. I’m not sure what went wrong there.

Both games have their quirks. These are both works-in-progress, but they are interesting and worth a look.


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24 thoughts on “Free Games: Open Arena and Nexuiz

  1. Phlux says:

    Typo in your header midway through: Open Arena -> Open Area

  2. wererogue says:

    It’s interesting that Open Arena’s bots are clunky – Quake III Arena had bots that were streets ahead of the norm at the time, and the bot AI is one of the few bits of code that isn’t open source from Q3A. I guess it’s tough to replicate.

  3. Phlux says:

    The one and only AI coding project I’ve had to do was in a web programming class in college. We basically learned javascript, and our big project was to build a browser game. It’s the classic “dots and boxes” game. You have a grid of dots, and you and an opponent take turns connecting two of them. If you successfully capture a square, it fills in with your color, and you get another turn.

    Our task was to make it so that the computer opponent “non-stupid”. It had to capture any square it could, and avoid leaving 3 sides to a square whenever possible, to prevent you from making a capture.

    Mind you this is not necessarily the best strategy to winning this game, but it at least simulates the behavior of a beginner level human player.

    Writing the “AI” was by far the most complicated part of the project. A basic two-player version with no AI was only a couple hundred lines of code. The computer opponent more than doubled that, I believe.

    I don’t blame id for not giving away the AI source. That stuff is hard to write, and theirs was really good.

  4. Joe says:

    Have you heard of Tremulous? It’s another open source game based off the Q3 engine. It’s team-based, deals with the standard marines vs. aliens theme. However, a couple things make it a incredible good game. It incorporates RTS elements with both teams building a base during a game. Also, the aliens are very well done, with smaller ones able to climb on walls and through vents while large ones able to jump large distances or simply dominate humans.

    Overall a very good game… it’s one of those ones I’ve found myself coming back to time and time again.

  5. Joe (different than #5) says:

    That Tremulous game Joe #5 was talking about sounds a lot like a game I’d heard of before… I believe it was called Natural Selection? Same idea, but on the HL1 engine.

  6. Dev Null says:

    Well your problem with ad relevance seems largely fixed – I’ve got an ebay ad on the sidebar for buying the original QIIIA for $7. Given thats the case, I wonder what the motivation is for the Open Arena guys to make a faithful reproduction? I mean interesting just as an exercise, and they might go on to add new cool things after, but just to save $7? Doesn’t seem worth it…

  7. Ben Finkel says:

    Aw, Shamus, I had lots of fun with Nexuiz, personally. While many levels in the campaign mode are hard (like the tower one with infinite rockets), I thought the game was very playable, and had decent AI that didn’t “cheat.” Or, I’m not noticing things. Still, I loved playing through, and am surprised that the mouse sensitivity feels “like a barge.” Setting it to 11 out of 20 worked for me.


  8. Blake says:

    “Making your code readable and easy to follow is extra work and requires dicipline”

    As a programmer, I completely agree that making your readable requires discipline, but if you think that you’re saving work by not making it easy to follow, you’re kidding yourself. Code readability is the sort of investment that pays itself back quickly and frequently.

    Or maybe I’m just bitter that the guy before me didn’t think the same way. ;)

  9. That Tremulous game Joe #5 was talking about sounds a lot like a game I'd heard of before

    Yes, Tremulous and Natural Selection are very similar (though Tremulous is open source), but that’s mainly because both games were… “inspired”… by the Q2 mod Gloom.

  10. Ian says:

    Indeed, Shamus. I played with the Quake source recently and it was a pleasure to work with, even with me not being particularly fluent in C. The Quake 2 source code looks to be about the same in terms of readability.

    @/dev/null: The main reason groups do things like that is (a) for something to do and (b) so that when it gets harder to find the game there will still be a way to play it. Sure, it might be easy to find copies of Quake 3 right now, but what about in a few years?

    Doom and Quake were both insanely popular games and you’d be hard pressed to find a copy in a store — new or used. I’ve been in plenty of game stores and haven’t seen either of them.

    Projects that aim to replicate without infringing are great ways to preserve old games. You might not get the same graphical assets, but the game still feels the same.

  11. bubba0077 says:


    I haven’t checked these open clients yet, but if they are set up the same was as Q3A was (and I suspect they are), you should be able to increase your mouse sensitivity past the “max” by setting a higher value in the .dat file (I forget the full name).

  12. Brandon says:

    World of Padman, Western Quake 3, and Urban Terror are all ioquake3 based games and are free.

  13. Brandon says:

    I should add that you have to do things a little differently for Western Quake 3, though. It’s not fully standalone yet.

  14. Ian says:

    @bubba: Correct, sir.

    Typing the command in the console will also cause it to be saved to the configuration file. Just bring down the console and type “/sensitivity” followed by a floating point value. Just typing the cvar by itself will show the current value.

  15. dagbrown says:

    To Blake: I believe I may have mentioned this to you before in person, but writing clean and maintainable code is absolutely vital, because the next person who has to maintain that code is most likely to be yourself. When you look at a piece of code and say “Man, who was the moron who wrote this?” and realize that you were the moron who wrote it, well…that’s just an object lesson that you shouldn’t have to go through more than once.

  16. Martin says:

    I tried to run Open Arena, but it complained about not having a default.cfg. That’s a classic id error message, but what did I do wrong? Anyone here get it to run on windows without having your own compiler?

    dagbrown“Man, who was the moron who wrote this?”


  17. croikle says:

    I second the recommendation for Tremulous; it’s a lot of fun, and the price is right for a cheapskate like me. It takes a little getting used to, of course, and good documentation is a bit tricky to find, but once you learn how it works it’s great.

  18. WWWWolf says:

    A bit of clarification: Nexuiz isn’t based on Quake III Arena, but rather DarkPlaces, a very heavily modified Quake I engine that has all of the most recent graphics tricks. (DarkPlaces is the Only Way to Play Quake 1. DarkPlaces has Bloom. Bloom makes life good.)

  19. Ben Finkel says:

    *Poke* Shamus, are you alive? I’ve really enjoyed these past posts, and look forward to your further musings!


  20. Rob says:

    I’d second (third?) the Tremulous/NS/Gloom nomination. It’s a great twist on FPS, and I really hope more games imitate the style.
    Also, there’s another game (similar mechanics, different genre) called Allegiance. Ok, so it isn’t really related to the Quake code as far as I know, but I’ve been waiting to spring this gaming gem on someone. It’s a combination space shooter/RTS (like a multiplayer ‘X’ without the trading), with one player on each side acting as the team leader, who selects what asteroids to build mines/bases/spaceports/spacestuff on, while the rest fly whatever ships the leader has purchased/researched. The main draw of the game is either defending the base long enough to get enough money to buy an assault ship or capital ship, or taking bombers to attack the enemy’s structures. It’s a bit more complicated than that, but in the interest of brevity I’ll just say, please, check it out. The site is

    Oh, one more thing, it has incredibly low system requirements, and fairly decent graphics. I can run it on a 400mhz computer with no slowdown. So it’s great for those of you who can’t run Tremulous. Not to mention it’s free!

  21. Mordaedil says:

    In the next free game article, maybe you could bring up Art of Theft?

    It’s old-school and fun to play and addictive.

    Also, wasn’t sure if HTML worked in blogs or not, if that above doesn’t look right…

  22. Mordaedil says:

    Right, it even removed the whole URL. It’s in website in this double-post.

  23. sdfsdfsdf says:

    on open arena mouse spinning outta control randomly wtf! ARGH

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