Oh, torpedo count limit, torpedo speed/power, submarine types (old diesel-battery to full nuclear), battery life, oxygen limit might be good too. And stop the blinking red hulls underwater - they reduce the need to use the sonar or periscope to aim.
Ok, since that the preference is a bit more arcade, having upgrades would be nice too. Upgrades such as type of torpedos (dumb, acoustic passive, acoustic active, decoys, battery, steam), hull (increasing max depth range), passive sonar range, hull coating (increasing stealth), submarine type (no. of tubes), would be nice... Enemy types can increase, and instead of a 1-hit death, a lifebar would be good. Its abit like ace-combat is to a true flight simulator.
After getting a master to a tavern, go to the workshop and unlock the master before proceeding to a new area. Else, you will need to go back and patrol the area again to unlock the master.
Becomes a little repetitive after a while. No matter how the path twists, it is essentially a straight path. Probably can add difficulty such as adding splits in the paths, and maybe even a slight story line.
Ok gameplay, but otherwise relatively uninteresting. Can be further improved for more variety:
1. physics modelling (e.g. ballistics),
2. graphics which are abit dull (e.g. rocket details, explosion, rocket exhaust),
3. zooming out (rocket should be about a fifth of the screen height or less),
4. inclusion of wind and solar (space) wind, which blow sideways
5. permitting controls with keys A and D instead of arrows only
6. a greater variety of collectibles, bonuses and upgrades.
7. individual component upgrades (as suggested by blondon)
8. having "crash" obstacles
9. in-game medals/achievements
Bug: Unit spawns at the most bottom of the screen. Then walks to the enemy castle and back without attacking any enemy, even when defending. Only happens to giants.
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