The popularity of Marine fast expand has increased recently. This post discusses this recent trend using data from the recent DreamHack Masters 2020 Summer Season Finals.

Background

Reaper fast expand is the standard opening in TvP for a long time (an exception). It is used as the opening block for essentially all variations of the standard 3-1-1 and the 1-1-1 into third Command Centre. We occasionally see proxy Barracks and Command Centre first opening, but there is little doubt that Reaper fast expand is the most common opening by far. So much so that we compare 15 Refinery Reaper and 16 Refinery Reaper more than we compare Reaper expand with other openings.

Marine fast expand is very rare. After all, a Reaper offers lots of value in the opening stage, and it is difficult to justify replacing it with a Marine. A Reaper provides scouting at the time when you need to determine Protoss’ tech path, so you can react accordingly (e.g., Cyclone and Viking against Stargate). Further, a Reaper is also an indirect threat to kill Probes if Protoss sends the Adept or Stalker over to Terran’s side of the map.

Data

Recently, Marine fast expand became a lot more common in TvP. Is Marine fast expand more popular than Reaper fast expand? No, absolutely not. The recent DreamHack Masters 2020 Summer Season Finals provides a snapshot of the current metagame. Out of 26 TvP games played, 15 were Reaper fast expand, 6 were Marine fast expand, and 5 were others (e.g., proxy). Thus, it is obvious that Reaper fast expand is still the most popular opening.

However, one cannot deny that the number of Marine fast expand is notably higher than what we normally observe. The data suggests 28.6% of the fast expand openings were Marine fast expand. More importantly, five different players from different regions used the opening in a premier weekend tournament. That means Marine fast expand is accepted as one of the mainstream options in the current metagame.

Rationale

As I had already mentioned earlier, a Reaper does almost everything better than a Marine at that stage. Then why would players replace the Reaper with a Marine? One reason could be the difficulty to scout Protoss’ main base with a Reaper. This is due to a combination of Protoss’ opening choice and wall off. The decreased utility of Reaper appears to be the most frequently mentioned reasons (I asked some players). While this seems reasonable, I wonder if the utility of a Marine is on par or higher than what a Reaper still can offer. A Reaper still poses a greater threat than a Marine to kill Probes, and its mobility still makes it far superior in scouting for proxy.

The second reason could be the difference in build time and resource. A Marine in comparison to a Reaper costs 50 gas less and takes 14 seconds less to construct. That means, the Reactor and Factory can be built earlier by replacing the Reaper with a Marine. This suggests it is a trade off between quicker tech and scouting.

The third reason could be the Marine count. With the earlier Reactor and shorter production time, you can start producing two Marines at a time earlier. This can potentially kill a Gateway unit walking up the ramp at the natural.

Build orders and implications

There are two main types of Marine fast expand. One gets the Reactor first, and the other gets the Factory first.

Reactor before Factory

14 – Supply Depot
16 – Barracks
16 – Refinery
@100% Barracks – Marine and Orbital Command
@400 mineral – Command Centre (@100% – Orbital Command)
@100% Marine – Reactor
@100 mineral – Supply Depot
@150 mineral – Factory

Example:

Factory before Reactor

14 – Supply Depot
16 – Barracks
16 – Refinery
@100% Barracks – Marine and Orbital Command
@400 mineral – Command Centre (@100% – Orbital Command)
@150 mineral – Factory
@50 gas – Reactor
@100 mineral – Supply Depot

Example:

When you go for the Factory before Reactor, the structures line up like the normal 16 Refinery Reaper expand opening. However, the Reactor before Factory feels different as you can produce two pairs of Marines by the time the Factory is completed. That means, you would have five Marines by the time you start producing from the Factory, and this opens up other build order options that we normally don’t see with Reaper expand. My personal favorite is a Marines and Hellions early attack (see vod below):

14 – Supply Depot
16 – Barracks
16 – Refinery
@100% Barracks – Marine and Orbital Command
@400 mineral – Command Centre (@100% – Orbital Command)
@100% Marine – Reactor
@100 mineral – Supply Depot
@150 mineral – Factory
@75 mineral – Refinery
@100% Reactor – 2x Marine
@100% 2x Marine – 2x Marine
@100% Factory – Starport; swap Factory on Reactor for 2x Hellion; build a Tech Lab with Barracks
Send the 5 Marines across the map.
@100% 2x Hellions – 2x Widow Mines
@100% Starport – Medivac

This timing is a little unorthodox, and it hits at a time when Protoss usually have two to three Gateway units. It is difficult to defend without a Shield Battery, so there is good potential to kill some Probes. If you were to compare it with the popular 4-Gate Blink, Protoss only have one Adept and one Stalker at that timing. The Widow Mines and Medivac (i.e., Widow Mine drop) follow up lines up well with the build.

TY did a very similar attack with a Reactor first opening (skip the Marine) two months ago against Stats, and the attack won the game out right (see vod).

It is worth mentioning that Hellion and Reactor Hellion are the common follow up options with Marine fast expand. This is because you did not scout with the Reaper, and Hellion is a good scouting alternative with this opening. This applies to both Reactor first and Factory first openings. See below vods for some examples from DreamHack and GSL.

INnoVation has also shown an interesting variation with the Marine fast expand opening. He does not go for the standard Reactor and Factory, but he gets an early Tech Lab for Marauders instead (see vods below). He takes map control with Marauders (with Concussive Shell) and Marine. The idea is consistent with the above builds, whereby you want to use aggression to scout for information. I must stress that this build gets the Refinery at 15 not 16.

14 – Supply Depot
15 – Refinery
16 – Barracks
@100% Barracks – Marine and Orbital Command
@400 mineral – Command Centre (@100% – Orbital Command)
@100% Marine – Tech Lab
@100 mineral – Supply Depot
@100% Tech Lab – Marauder and Concussive Shell
@150 mineral – Factory
@75 mineral – Refinery
@100% Marauder – Marauder

We rarely see innovation with openings, so the recent games are refreshing. I look forward to see more interesting variations that we normally don’t see with Reaper expand.

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

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