15 gas build is arguably one of the most popular builds now for TvT. It can transit into Marine Tank or mech composition. It basically works like a 1-1-1 build with an earlier command centre. Given that it is a 1-1-1 build, there are many things you can do early when the Medivac is out. This post discusses some of the better variations of a 15 gas build.

There are many VODs available on this build since the release of Heart of the Swarm. Flash, INnoVation and Jjakji were using this build way back MLG Dallas. I will link some of the more relevant ones in this post. Let’s start with a basic build order of a 15 gas build before I mention the variations.

Basic build order

10 – Supply Depot

12 – Barrack (@100% – Marine)

15 – Refinery

16 – Orbital Command

17 – Supply Depot

After 2 or 3 Marines have been produced* – Reactor on Barrack

@400 mineral – Command Centre (@100% – Orbital Command)

@100 gas – Factory

23 – Supply Depot

@100% Reactor – 2x Marines

@100% Factory – Starport

Swap Factory onto Reactor (after the pair of Marines has been produced).

Explanation

In comparison to a typical 1-1-1 build, this build has an earlier command centre but a later factory. This is because of getting the first refinery at 15 and not at 13. An early reactor gives you more options as you can swap any building on it. I left an asterisk to the number of Marines produced before a reactor is built as you can get either two or three.

First, in terms of resources, the reactor lines up better if you just produce two Marines. However, three Marines line up better later on for some variations which I will discuss them below. When reactor is built after three Marines, more than 100 gas is being piled up. Intuitively, it seems better to build the factory with the 100 gas, and use the next 50 gas for the reactor. However, the build order doesn’t feel as sleek as reactor first when your Medivac is out. You have to try it out to understand what I mean. Second, three Marines deal with Reaper much better than two.

After the factory is being swapped onto the reactor, that is when you have to decide which variation you want to do.

On a side note, the second refinery can be built at the same time as the starport depending on your build order.

Both INnoVation and Flash were using 15 gas opening against each other in Proleague.

The build orders of the variations continues from the above basic build order.

1. 8 Marines + 4 Hellions + 1 Medivac

Flash used this variation in the above video. In order to reach eight Marines and four Hellions when the Medivac is out, the reactor has to be built after three Marines. If you do start the reactor after just two Marines, you have to do two rounds of Marine production (four altogether) when the reactor is completed before swapping. I prefer three Marines before reactor because of Reaper.

Swap Factory onto Reactor (after the pair of Marines has been produced) – 4x Hellions

Produce three Marines from the barrack (without add-on).

@100% Starport – Medivac

There are several ways to play this. You can just attack from the front at opponent’s natural. Or you can do a two pronged attack by dropping eight Marines in opponent’s main, and move the four Hellions to the natural like how Flash did it. I think this is the best option. It’s less effective to drop Hellions and walk Marines to the natural due to the relatively low mobility of the Marines.

If the map allows, you can do an elevator drop as demonstrated by INnoVation in the following video.

2. 2 Widow Mines + 4 Marines drop

INnoVation did this against Flash.

@100% Factory – Refinery

Swap Factory onto Reactor (after the pair of Marines has been produced) – 2x Hellions

@100% 2x Hellions – 2x Widow Mines

@100% Starport – Medivac (slight delay because of the gas spent on Widow Mines) and add a Tech Lab on the Barrack.

@100% 2x Widow Mines – Swap Factory on Tech Lab, and Barrack on Reactor.

Load the Medivac with two Widow Mines and four Marines. Drop one Widow Mine at each mineral line, and use the four Marines to pick off the injured SCVs. Widow Mine’s splash damage is not enough to kill SCVs.

The idea is to force some scans while you transit into Marine Tank production early.

3. 4 Hellions drop

Same as the Widow Mines drop above, but instead of getting the Widow Mines, you get the second pair of Hellions. INnoVation did this against Flash in MLG Dallas.

As I have mentioned earlier, 15 gas build can transit into both Marine Tank or mech composition. In this match, Flash transited into mech, while INnoVation goes for Marine Tank. Both start with 15 gas build.

4. Defense

This is viable if opponent techs quicker than you do with an earlier gas (usually 13). If you choose any of the above options, your build will cross with opponent’s. Given that his tech kicks in first, you will take more damage than him. Let say the opponent is also doing a 8 Marine and 4 Hellion timing. S/he will be at your base when you’re just moving out with yours. You have nothing to defend and hence you will more or less have to do the same amount of damage at his base in order to stay in the game. However, it should lead to an unwinable situation since you take damage first.

Thus, it is better to defend than to attack against such aggression. Your unit count can definitely match his/hers with your defender advantage. You are ahead as long as you don’t take substantial damage from the aggression due to the earlier command centre. You can produce a Viking instead of a Medivac as Viking works better when you’re defending. Also, in the Proleague match between Flash and INnoVation mentioned above, both players produce a Viking right after the Medivac as it helps to defend the incoming drop when their builds are crossed.

Jjakji did a brilliant job at defending against MarineKing.

Summary

15 gas build is a popular build for TvT with various options to follow up. You can use this build but with different variations in a series.