This is a safe fast expand build which transitions into a marine, marauder, medivac style against protoss which deals good damage through drops and defensive capabilities as well as the ability to achieve a quick third.
10 – Supply depot
12 – Barracks
15 – Orbital command upgrade
15 – Marine
16 – Supply depot
17 – Command center
21 – Bunker
From here you have a relatively safe fast expand up and some defensive capabilities with the bunker. If you scout aggression or forward pylons you may want to get 2 or more bunkers up to be able to defend as well as pulling SCVs to repair.
22 – Barracks x2
23 – Refinery x2
24 – Orbital command
28 – Tech Lab on barracks
34 – Stim Packs
45 – Factory
48 – Techlab and reactor on barracks
55 – Reactor on factory
64 – Switch starport with factory
64 – Concussive shells research
64 – Engineering bay
69 – +1 Infantry attack upgrade
You should start to be aggressive using your first two medivacs and push out with units. Your +1 attack should finish around the time when you arrive at the protoss' base. Follow up with a third base if you feel it is safe and continue to add more unit producing structures and dropping using your medivacs if possible as well as continuing upgrades.
