I mentioned the new double Refinery Reaper opening in my last three TvT articles, and quite a number of you had asked me about it. This post discusses the opening.

Build order

The new opening is not that new, as top players have been using it for months. The key difference is shifting the first Refinery from 15 to 16 supply. This delays the Factory by 10 seconds. The vod below shows both the new and old openings in the same game for easy comparison.

New opening

14 – Supply Depot
16 – Barracks
16 – Refinery
17 – Refinery
@100% Barracks – Reaper and Orbital Command
20 – Supply Depot
@100 gas – Factory (then pull 3 Scvs off gas)
@100% Reaper – Reaper
@400 mineral – Command Centre
@100% Factory – Hellion (put Scvs back to gas)

Old opening

14 – Supply Depot
15 – Refinery
16 – Barracks
17 – Refinery
@100% Barracks – Reaper, Orbital Command and Factory
20 – Supply Depot (pull 2-3 Scvs out of Refinery)
@100% Reaper – Reaper
@400 mineral – Command Centre (put the Scvs back in to saturate both geysers)
@100% Factory – Hellion

Implications

While the difference in build order notation seems small, it has some interesting implications on the opening metagame. To understand the implications, let’s trace back to the original double Refinery Reaper opening, whereby you take the first gas at 15 then the second at 17. When it was first used, it was always followed up with aggressive 1-1-1. Players quickly figured out that two gas means fast tech aggression (e.g., Cloak Banshee). When Cyclone was the defining unit in the TvT early game back in patch 3.8, having early access to it with the double Refinery opening created some issues in the metagame. The next innovation was to use the same opening to get the early Factory, but you take 2-3 Scvs off gas to put down a Command Centre. This changed the then assumption that double Refinery opening is a fast tech delay expansion opening. There are two main benefits of using the double Refinery expand over one Refinery expand. First, you have two Reapers and a Hellion early on, so you would have the map control over the one Refinery expand player. Second, you have early access to Factory, so you can defend against proxy opening with Hellions. I will go through how the new double Refinery opening fares against the old one based on these two points.

In the current metagame, the map control advantage over one Refinery expand opening is debatable. This is because the one Refinery expand opening player often goes for Reactor Hellions against a double Refinery opening. Apart from the temporary advantage when the double Refinery opening player has two Reapers and one Hellion, the map control advantage is unclear once the one Refinery opening player has four Hellions. Thus, the slight delay of the Factory with the new double Refinery opening does not really weaken the map control issue against an one Refinery opening.

I had discussed extensively about how to react against proxy Reapers. In that article, I highlighted that the double Refinery opening has an easy time against proxy Reapers, because you simply have to continuously make Marines and Hellions. Does the slight delay of Factory in the new opening is weaker against proxy Reapers? If you were to strictly compare the two for this specific situation, the answer would then be yes. The 10 second delay on the Factory (i.e., delay in Hellion production) would force you to pull Scvs to defend for a longer period of time, but the difference is not big enough for this to be a serious issue. The old opening also allows you to proxy a Starport to counter attack with a Liberator, but players nowadays time their Factory nicely to counter this move. Thus, you do not exactly lose out on the Liberator counter attack option. Below vod is an example of how the new opening deals with proxy Reapers.

Based on what I mentioned so far, the new opening appears to be tiny bit worse off compared to the old opening, then what are the upsides? The Command Centre is down slightly faster for the new opening than the old opening, but the difference is really marginal. The other upside is how the resource line up a little better. Every player who has used the old opening would know that you cannot afford both the Reaper and the Factory immediately when the Barracks is completed. It is normal to prioritise the Factory over the Reaper, so that means the Reaper is slightly delayed. There is no delay in the Reaper for the new opening, and this subsequently leads to an earlier Reactor. The difference is almost negligible, but the timing could make a tangible difference against three Reapers and two Hellions attack. The two Marines are just in time to join the battle against three Reapers and two Hellions. Overall, the differences between the old and new openings are marginal.

It is worth mentioning that the old opening is better than the new one for using attacking follow up options. The 10 seconds difference in tech is huge if you are attacking. If you attack with three Reapers and two Hellions 10 seconds later, opponent would have two more Marines. The new opening also does not line up for quick tech 1-1-1 as well as the old opening. This 10 seconds difference in tech is mitigated when the player wants to be defensive, because the attacking player’s units take time to move to the other side of the map. This then goes back to the issue with game theory about whether to attack or defend and with what units in a double Refinery mirror match up. I had written an update about this here. Therefore, if you scouted that the opponent is using the new opening, there is a good chance that s/he is not going to be aggressive early on. All in all, if you are really comfortable with the old opening, you can just keep doing it.

This article is translated and posted on scboy.com by 绝迹.

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