Again, I don't know if there are already posted. If they are my apologies.
1. The well known worker exploit during battles (this idea worked in many previous versions as well): Grab a worker (usually very easy) and leave it unprotected into the area of the opponent. The idea is that AI is so stupid that will do whatever possible to get it, usually uncovering his well fortified forces just to get exactly into the fire of your archers/catapults/cannons. In my last game I had a terribly timed attack against China at the time they had those amazing Chu-Ko-Nu. Still, they wasted ALL of them just to get a useless worker (which they didn't eventually).
2. The Metallurgy skip: for some reason, I believe due to oversight, Replaceable Parts (i.e. Infantry) doesn't depend on Rifling. In other words, if you skip Metallurgy you can arrive to Infantry without getting Riflemen first. This can be very useful to catch the opponent with outdated military for a short period in an almost equal science race - but you have to be very fast since you can't upgrade units.
1. The well known worker exploit during battles (this idea worked in many previous versions as well): Grab a worker (usually very easy) and leave it unprotected into the area of the opponent. The idea is that AI is so stupid that will do whatever possible to get it, usually uncovering his well fortified forces just to get exactly into the fire of your archers/catapults/cannons. In my last game I had a terribly timed attack against China at the time they had those amazing Chu-Ko-Nu. Still, they wasted ALL of them just to get a useless worker (which they didn't eventually).
2. The Metallurgy skip: for some reason, I believe due to oversight, Replaceable Parts (i.e. Infantry) doesn't depend on Rifling. In other words, if you skip Metallurgy you can arrive to Infantry without getting Riflemen first. This can be very useful to catch the opponent with outdated military for a short period in an almost equal science race - but you have to be very fast since you can't upgrade units.