Early E-Bay (vs. Protoss)
A Barracks (3) and Marauders can be added earlier for offence or defending Stalker (with Blink) all-ins. But, generally will want to wait until all necessary upgrades and Engineering Bay Upgrades are started before committing to heavy 5 Barracks production.
Using a Reaper to scout and Marines and Bunkers for defense. Take Refineries quickly to tech up to Stimpack and Medivacs quickly.
Basic Build Order
- Take 1 SCV off Refinery (1) after Reaper (1), and add back after Refinery (2) finishes, this just makes the build line up better as buildings finish to line up with 100 gas as needed.
- Barracks (2) and Infantry Weapons cause a slight cut in SCV production, Marine production starts around the same time, and you do not have the minerals to build all the above; so build Barracks, Infantry Weapons, Marines then finally SCVs and go back to full production soon.
- Reaper (1) is for scouting purposes and should not be sacrificed unless you are ready/sure what needs to be done to survive to the mid-game.
- React as scouting - for example stop Marine production and start Missile Turrets (1-3) in mineral lines, if you scout a Stargate to prepare for Oracle (1) that is now useless with good Turret placement.