Just finished the game, didnt get the medal because of the timeout issue I guess and after finishing the game resets all game progress :/ Should have read NeonSpider `s game review before playing...
edit: just replayed it. Its enough to have mages and 1-4 paladins from stage 4 onward (respawn 1 every now and then) and retreating the mages when the enemy hero gets to close. That way you dont have to grind gold.

After years i return to play this and discover a few things, the most efficient unit is the mage, in almost all scenarios i win only using 4-10 mages and nothing more, exept the desert and the last level.
the four level is the best level to grind, using 6 - 10 mages, keep them near the golem and wait to enemies to die and get 99999 money for the last level

Almost all other units are useless exept the mage and the bottom-right warrior, in the desert level go with expensive units because the dragon counters the mage, in the last level buy the 980$ warrior until you have no more population and attack, in all other levels buy 4 to 6 mages, and some expensive unit if there is a powerful unit like the knight with the hammer

Fun game but the balance it's a bit broken, with some fixes it would be a very good game

Winning strategy (Maybe not optimal. Very grindy)

Start with 4 mages. The one that costs 600. Yes don't care that you lose your starting melee fighters or that your golem takes a bit of damage as you wait and buy the 4 mages, buying a new mage each 600.

Just wait. With this setup and at this stage you are invincible. You could leave it running there all night to grind gold if you want.

Advance when you're ready and clear stage 1.

Now for the rest of the stages, you can use mages early on but later stages you'll want to switch to that bottom-right expensive fighter, a bunch of those dudes, send 'em out.

Then whenever you're short on cash, play stage 1 again, grind the cash, play the next stage, throw out those expensive dudes and so forth. You can also grind on other stages but you may not have an invincible setup you can just set and forget. If your golem is ever taking damage, even occasionally, means you cannot just leave this setup running while you walk away.

The game does save after each stage but if you ever lose, you lose ALL progress, so it is very important to never lose a battle. Especially if you've spent a lot of time grinding.

Better to over-grind and send in way overpowered everything and completely overdo it than to risk a loss.

Before playing the final stage, make sure to refresh your browser, that way any possible medal connection issues should be not a problem. Then proceed. And you must wait for the entire ending and the game does go back to title screen, before medal is awarded.

no medal lol

Now what kind of stupidity is that? I sent 8 units of the same type forward and just because they were located at the same spot they got killed AT THE SAME TIME? It is just idiotic!

PS

But the same rule doesn't seem to apply to my units hitting enemy units.