Two player and powerups for Harrier Attack Reloaded

Wingman feature

Over the past few months I have been developing a wingman feature for Harrier Attack Reloaded. That second harrier that sits on the deck of the carrier got me curious. I wonder if it could be used for a two player game? So that's what I decided to do.

My initial goal was to get the wingman flying under the control of the CPU, kind of like a powerup feature similar to R-Type.

The first step was to get it to take off, fly in formation with the player, and land again successfully. 
Once this was accomplished, I programmed tracking and targetting mechanisms, so it could shoot rockets at enemy planes. I modified the existing rockets and bombs functions used for player one, so they could be used by the wingman harrier.
Then, using my maverick targetting mechanism for rockets, I adapted it to enable the wingman to target enemies on the ground and bomb them into oblivion.
Finally, I added extra collision detection around the wingman sprite so he knows to avoid oncoming rockets, planes, the landscape, etc.
It worked quite well, but the wingman still crashed a bit, causing problems for player one. So I disabled collision detection with the main harrier.

Powerups

If the wingman crashes we need a way of respawning him, so I modified the existing parachute sprite for this purpose.  This enables the wingman to get back into the game. I also created other powerups, and colour-coded the parachutes so the player could get additional help through the level. Yellow chutes restore health, red replenish rockets, and blue restore bombs. It seems to work quite well. 

There is also a two player mode, where a second person can control the wingman plane. Setting this, and then redefining keys allows you to change the controls for player two. There is a slight drag on the controls for player two when taking off or landing. This is to give a sense of speed, as it didn't feel right that player one was speeding up or slowing down, but player two remained stationary. We'll see how that works out.