Exploits

You horrible cheater, you.

Land Reclaiming
In winter, any water that isn't a river or rapids tile will freeze over. If you dig or build anything on these tiles, when they thaw, they will not be water tiles anymore - they'll have turned into ground tiles.

Battleship
This takes advantage of the fact that NPCs don't have ranged weapons (yet). First, you get a raft or punt, then drop arrows and javelins on it, in the order of 100+. Then, row next to the shore of a Njerpez village (but not actually adjacent to a land tile), and start shooting. You will be able to kill them, but they can't hit you back. Furthermore, ALL the Njerpez in the village will come over to the shore to try to kill you, but won't actually get close. For extra cheapness, let loose a couple of dogs.

This exploit is much less advisable in the new version, 3.12b as some NPCs have ranged weapons. However, it's still fun :)