time to try this out i guess :)

Battle for Wesnoth is fun and well polished. It comes with several campaigns and it is easy to add more. Start with the tutorial to get the most of the game. Turn-based battles, in the vein of Fantasy General. Lots of factions and unit variety.

I remember playing some survival extreme mods (basically, you have one unit facing hoards of enemies, but you can pay for upgrades and the enemies also get stronger and keep spawning), and I remember one issue with the game; the AI is too smart for that style of gameplay. The AI tries to find the best unit to use to attack the player, which makes sense for more typical campaigns, but it doesn't really need to do that for survival extreme, and with the AI having such large numbers of units, the time it takes for the AI to decide what to do slows things down significantly. The player has just one unit, which means the player's turn isn't long, but then the AI's turn takes way too long.

The solution, of course, would be to make an alternate "dumb" AI, which just moves units toward the player in order, attacking the player with whatever unit happens to be first in the order. Doing this would greatly reduce the time the AI takes to decide what to do, and would make the game flow better, while the loss of smarts wouldn't be a big deal on this mode.

(Of course, the default AI behavior should still be kept, and would still be a good default, as it makes sense for more typical campaigns (including the ones shipped with the game); it's just that there's this one pathological case where it's a poor fit.)

Not that I'm aware of. Which is darn infuriating.

I think it's definitely a good game. One of the best free games I've played, with lots of variety and tactical depth.

One issue I found though was to do with balancing. Because your units improve as you use them, some campaigns seem to rely heavily on maintaining momentum from battle to battle. So, if you lose that momentum in a tough battle, where you scrape through it, but lose some of you better units, it can be difficult to impossible to recover, and you can get into a downward spiral. That's the only criticism of it I can think of though.