Thinking Without Portals – How The Portal 2 Gel Mod Aperture Tag Came To Exist

Recently released on Steam, Aperture Tag rests somewhere between a substantial mod, DLC, and a full game release. It uses Portal 2's assets and and setting, but takes one if its mechanics – the use of the blue and orange gel – to create a completely original experience forcing you to examine Portal puzzles in a whole new way.

Instead of using the portal gun to make your way through Aperture's labs, players have a new paint gun letting them fire off the speed-boosting and bouncing gel nearly anywhere.

The game is the brainchild of Eugenio Roman – a dedicated modder of Valve's games – who decided to step up his tinkering to create a full experience with Aperture Tag. We spoke with Roman about building the game, how involved Valve was with the project, and how the game came to life.

Correct me if I'm wrong, but the ability for players to paint the walls with the blue and orange gels from a gun, as you do in Aperture Tag, was supposed to be part of Portal 2 at one point, right? Valve cut the mechanic. What made you decide it was worth exploring?

Eugenio Roman: I am not exactly sure about this. There is a weapon_paintgun in the files, and as an entity in the Portal 2 level editor, but it doesn't do anything. So certainly they had plans to do a paint gun, but it looks like it got cut out of the game.

The story for Aperture Tag starts way back before Portal 2 was released. In my wait for Portal 2, the new gel mechanics where shown and in the announcement they said the gels came from the team behind TAG The Power of Paint, who were hired by Valve. I downloaded TAG immediately and I had a ton of fun playing that game. TAG was very short. It’s only about 7 maps, and when I finished it, it left me wanting more. For about a year or more I had this taste in my mouth about wanting to create maps for a paint gun.

Almost three years ago I found this video and asked the creator (who I knew from the Portal 2 mapping community) if he was going to use his device to create maps, he said no and I asked if I could use it and he gave it to me. After some changes to the gun's logic and behavior I released a map to ThinkingWithPortals.com (The Workshop was not available for Portal 2 yet). The level was highly praised, even though the gun was extremely unresponsive. It was great fun, and I knew this was valuable and definitely worth exploring.

A bit of time goes by and I am lucky to be in the closed beta for the Perpetual Testing Initiative. There I had the chance to meet some Valve employees and after some discussions, I inquired about a paint gun. I mentioned that all that was needed was a working entity (the previous weapon_paintgun) and I said the community would make the maps.  When I learned that wasn't going to happen, I decided to take matters into my own hands. I built some extra levels, but nothing too serious. I started beta testing the Left 4 Dead 2 workshop and the Counter Strike: GO (CSGO) workshop and the CSGO one was taking more of my time. I entered the first CEVO/GameBanana contest for CSGO in early 2013. I worked hard for about 3 months on a single map and in the end, the contest left a bad taste in my mouth. When maps that obviously violated the rules didn't get taken out, I decided that was the end of contests for me.

I returned back to the paint gun and had to think what I would do. I could release the maps in episodes or just create a full modification of the game. I decided a modification would be the best path, as it would allow me to keep editing the first levels based on new experiences and changes made to the gameplay as the game progressed.

In May 2013 I wanted to visit Valve, so I bought a plane ticket and visited. I had planned a day for Valve and the other to explore Seattle, but to my surprise they brought me in the for two days. I talked about my visit on Reddit along and posted some pictures. That visit was a huge confidence booster and from there I started dedicating basically all my free time to Aperture Tag. By the end of 2013, I already had all the campaign mapped out. It wasn't pretty, but it was playable. I made something that I enjoyed playing and the project just grew bigger and bigger.

The Pneumatic Diversity vents/tubes used to travel from location to location – wasn't that a feature ultimately cut from Portal 2, as well?

From what I recall from the first trailers, the Pneumatic Diversity Vents were supposed to suck through the portals. You could portal near a turret and it would get sucked through. I am not sure why they were cut in the end. I think the vacuum tubes just didn't have that much diversity in them as a testing element. In the final game there is a Vacuum Ride where the player and Wheatley get sucked through.

Before Portal 2, I had played through Portal many times over, and I always found the elevators very slow. In Portal 2, the elevators were much better, but I still had this predisposition to think they were too slow. Which is why I decided to use Vacuum Tubes in Aperture Tag, to make it feel much faster.

For more on how the game was built and how long it took, head to page two.

How long has the game been in development?

This is hard to pinpoint. Do I consider the time I spent working on the game before knowing it would turn out into Aperture Tag? I've been dedicating all my resources whenever I can since about March 2013, but I didn't start from zero, as I already had the paint gun, some levels, and experience under my belt since early 2012.

How was the game built? Did you just tweak Portal 2's level building tools, or was it a much more in-depth mod?

The game was built using the Portal 2 authoring tools. I had my Portal 2 game modified for more than a year, so it was like playing Aperture Tag. When I added a texture, particle or sound, I added it to my build in Portal 2. Then I simply grabbed the content folder from my modified Portal 2 and uploaded it to Steamworks for my own Application on Steam.

Valve didn't release the source code for Portal 2, so all of Aperture Tag is done in the level editor called Hammer. The paintgun was created there using a system of onput/output and the combination of many tricks I learned through years of experience with the Hammer editor since my days of Counter Strike Source mapping. The in-game level editor did involve the modification of scripts and map files that the level editor loads, but we had a programmer (Benjamin Thomas Blodgett) who created an executable to detect for various cases to modify the map file the level editor makes before passing it over to compilation.

Is it considered a mod, DLC, or a full game? Or is that just a semantics argument?

I have found this to be an extremely sensitive case – one costumers weren't ready for. Aperture Tag is the first of it's kind. Previous mods were mods and then later developed into a full project, like The Stanley Parable, Black Mesa, and many other Valve games. But there really hasn't been a mod that monetizes right away. Personally, I find the term "Community made DLC" be the best fit. Because when you look at other DLCs, for Borderlands, Call of Duty (Or Valve games like Left 4 Dead 2 and Portal 2) they generally add an extra campaign, new weapons, dialog, etc., while still using many of the original game art assets. I think that in the end, we just have to see what term the players adopt.

I was a little confused by the game when I first saw it – it's a Portal 2 mod, but it's not built by Valve, but it is being sold separately from Portal 2 using Portal 2's assets and setting. Was Valve involved in the mod's development? Did they have to offer their approval?

Valve's involvement was quite limited. They are a small studio and I am sure they have really cool confidential projects going on internally, so naturally they don't work on external projects much. From my testing for the Perpetual Testing Initiative, and my visit at Valve, I already knew a handful of employees. But most of my time was dealing with Steamworks and incorporating the game into Steam. Along with business questions about licenses, I did ask for a favor from one employee. There was a problem with the workshop. When you tried to play a workshop map the screen would just turn black with no error code whatsoever telling you what is going on. I had to ask for some time, but in the end one employee helped out by modifying some dlls files, correcting this bug. Now the workshop will work on all future Portal 2 mods.

Was there any red tape related to selling a game with original mechanics using the assets and setting of another game? Is there any issue of copyright infringement, etc.?

Thankfully, Valve is quite flexible in this regard. They see the value in the modding community and when a mod or game releases commercially, they see a share of the percentage. Using assets from a Valve game just means they get an extra slice.

Head to page three for more on the game, and to find out which is better: Portal's "Still Alive" or Portal 2's "Want You Gone".

The game's story seems like it could fit in the Portal universe. Does Valve consider it canon?

This I actually haven't discussed with Valve, so you may need to ask them yourselves later on. I created the story line to be after the co-op bots find the test subjects at the end of their campaign. You play as one of those test subjects, and Nigel was made by GLaDOS to oversee the new test experiment. I added just enough hints of when it took place, but also tried to steer away from touching Chell's storyline, as I don't think that is up to me or anyone other than Valve to talk about. The Perpetual Testing Initaive stuff is easy. You are in one of the universes where instead of a portal gun you have a paint gun, but everything else is the same (Even Cave's lines.)

One of my favorite parts of the game was revisiting Aperture and seeing it from different angles.

Thanks! I had to replay Portal 2 to think which two chambers could be solved with a paint gun instead. I made a list and chose two chambers. One of them was just boring to solve, so I chose another one instead.

Were there any secrets or Easter eggs I might have missed when revisiting familiar Aperture lab locations?

I am not sure. I tried to keep the Portal 2 chambers as close as possible to their original versions. Here is a complete guide to all the Easter eggs in the game.

The timed obstacle course that occurs right before the last section of the game – it is radically different from Portal's typical gameplay. Why did you allow players skip it?

The timed obstacle was a dodgy idea at first. It was an area that required you to try it many times before you managed to solve it. I tried to design it so players would know intuitively what to place next, by using colored walls and lighting. I also kept the hard bits at the beginning so you get a chance to practice the hardest parts the most. I knew some people would still get frustrated. I made the option to skip it, so that more casual players wouldn't get stuck, but still get to experience the thrill of the course. And also to serve as a 'GPS', so you can look at the solution as to how it's done and then try to replicate it. The map name is 'gg_all2_escape', so if you want to jump directly to that map and try again, you can use the map command in console 'map gg_all2_escape'.

I never got a good look at Chell (it was Chell, right?), but it looked like she was changed slightly. What was changed about her? And did you ever consider using a whole new character model?

We changed the skin of the player model. So we changed her hair color and her clothes, just enough to imply that it isn't Chell. We would have wanted to include a new player model, but the modelers were very busy doing the final touches to the A.L.S.S.E.R. room.

Valve is known for snapping up talented developers who build interesting mods using its tools. Is that a hope with the release Aperture Tag? Would you like to work for Valve?

That would be a dream come true and I do hope that Aperture Tag will get me, and any anyone else on the team, closer to their doorstep.

What else are you working on/have you worked on? Is this your first release?

Aperture Tag is my first game release on Steam. I've done many maps and levels for various Source Games. I’ve made countless Counter Strike Source maps, specifically for Zombie Escape – a server sided mod for CSS, a map pack for Portal – which got me 2nd place in a mapping contest at ThinkingWithPortals.com, many CSGO maps and Portal 2 maps, a whole Left 4 Dead 2 campaign called A Dam Mission, and finally Aperture Tag.

For the future, I plan to keep updating Aperture Tag where needed. I also am playing around with Unreal Engine 4 preparing myself for my Oculus DK2 to arrive. That is a whole new interesting area to explore and learn that no one is currently teaching.

What's a better song – "Still Alive"? Or "Want You Gone"?

I prefer Still alive. And in my opinion, the Cara Mia Addio song would have been sufficient for Portal 2.

What's a better game – Portal or Portal 2?

They are both excellent. I was blown away when I first played Portal, but Portal 2 is much bigger and epic. I'd say, play them in order.

You can download Aperture Tag by heading here.