The battle mat is the Cigar Box 'European fields' one.
Maurice is probably my favourite set of miniatures rules. It is designed for the 18th century, but it has rules for Pikes (to cover the GNW and the War of the Grand Alliance), so it works fine for ECW.
The rules are card driven - each turn you can pick an action - Bombard, Move a force, Rally a force, Charge with a force, play an Event, or pass.
A 'force' is a group of units of the same type in the same formation all close together (so a second line is useful to keep force integrity when units start dying). If you play an event or charge, you draw no new cards. If you move you draw 1, if you rally or bombard you draw 2, and if you pass you draw 3.
Cards are also used as modifiers (allowing passage of lines, improving combat or shooting, or inhibiting the enemy, and so on)
So you if you act aggressively you quickly find you are running out of cards and must pause, but that lets you enemy rally.
Also, you only get to do things with one force a turn, so co-ordinated attacks are very hard.
As units die, your force morals is depleted and when it reaches zero the army breaks. Alternatively, if you've been through the deck 2 and a bit times, night falls, and the victory goes to whoever controls any objective(s).