So you can start a game, move around, shoot at bad guys, and they can shoot at you. All good, but there are still some game mechanics that I need to work on before I can start on designing real levels.
Right now I’m implementing the power-up system. The way I envision it working is this: Every enemy will, when destroyed, drop one or more “energy crystals” relative to how large/difficult to kill they are. Collecting these charges up your power-up bar, but they start to decay after being dropped, so grabbing them quickly is vital. Once the power-up bar is full, your weapon levels-up and the bar is reset, this time taking twice as much “energy” to fill and reach the next level. The bar will also slowly drain, and if it reaches zero you will “level-down” to the previous weapon. You can also trigger a superweapon or smart-bomb effect by holding the mouse button, but this will drain your energy bar even quicker. Dying won’t completely reset your weapon, but will bump it down a notch.
This adds an element of strategy and a risk/reward structure to power-ups. Should you use the superweapon to clear this difficult wave of enemies, or save your energy to keep your main weapon leveled-up? Plus the decaying energy crystals encourage the player to take risks and fight up-close and personal in order to grab them quickly for the greatest effect. The continuous drain might be a problem during boss fights, but I can get around that by having smaller enemies, or maybe homing missiles launched from the big bad, drop energy during the battle.
The biggest challenge will be balancing all this. If you can help by playtesting, I’d be very grateful.