Variant2 is an epic ruleset, its tech tree is about twice the size of classic, and playing it can take (much) more than 1,000 turns. Expect a turn end countdown (2.6 feature) of more than 60 seconds on a box needing about 10 seconds for classic.
Among other features variant2 has ocean cities with sea constructors, which cannot be attacked by land units. Balloons are a kind of air explorers, easy to kill, but fun to explore unknown territories, or to annoy hostile land units by sticking to oceans or lakes. Variant2 uses the tired attack feature, i.e., the attack strength of units with less than one move point (in fragments) is reduced accordingly.