Hello, I've not played very many games, but here's what I've gathered about playing 2.1 esc freestyle unlimited, 3-6 players:
The usual escalating tactic everyone knows, the chain reaction of killing and cashing cards... needs some alteration on 2.1. The map is so big, the bonuses are so big, that card cashes won't come into play for a long time. You can still pull off the chain reaction, but you need to time it perfectly.
While waiting for that time, you build your assets, try to grab as much territory and continents as you can. But don't spread yourself too thin, so it's too easy to break your bonuses. It's a delicate balance. Use your drop as your advantage, even if you get a bad drop, make the most you can from it.
Then, when you have a steady foothold and a steady income of troops, start harassing on your opponents. Break a bonus here, take a territory there.
As the time comes near, you pick the best target, and start preparing in advance for the slaughter. Position some troops strategically, but don't be too obvious. Do it subtly. Throw smoke, make your opponents think you're after someone else than you're really after.
Wait for it... wait for it... and bang!
You might not be able to sweep the whole board in one turn. It doesn't matter, just weaken the leftover opponent(s) enough so that you can get them the next turn. Beware, if any have 3 or more cards, they could have a set. Take precaution. Don't waste all your troops trying to take them out, if it starts to seem like you can't do it.
It could even take more than 2 turns. Ie. you kill the first one on 1 turn, reinforce to attack the next guy with the troops you got, then take the next guy on the next turn, go on to sweep most of the board, again reinforce/deploy in the right places, and on the 3rd turn you finish the job.
One more thing, with so many territories in the map, you really need to work out your attack routes in advance, that is, before you deploy. Otherwise you may find yourself in a situation where you would have had enough troops, but you end up advancing yourself into a corner...
The most important advice: THINK before you act!
Sorry if this is off topic because of the escalating thing, I'll play some flat rate 2.1 soon, I'll let you know what I think about it after.