Battleship game graphics

Battleship game graphics

Hello, we are organizing programming contest RedBot for Czech and Slovak students and this round we are "playing" battleship game (we have extended origial rules though). Students are supposed to program strategies which will do the fight.

Part of the code we are providing to them is visualiser to replay fight performed by two strategies where we have only real basic graphics. We will use that to generate videos of final fights to upload them to youtube as well (e.g. see our previous round with fighting worms). What we need is a set of 20 x 20 pixel images which can be used to render ships, sunken (parts of) ships, sea, explosion of one field and mega-explosion of 4 fields (as you can see on the image). Both in two colors to distinguish players (but I can do some colouring myself for sure).

How should the images look like? It could be fantasy or sci-fy, it can be funny or serious - as per your prefference.

Thank you a lot for your help,
Jan