You drive a helicopter and select the favored available zone you want to do. At the end of each level awaits a final Boss (That appear in a specific order) and you can't restart a level you have already finished. You can travel all around the world and kill seagulls by crashing into them with the chopper, they will try to fly away from it though. The user generated island was also on this map.
It's like the Campaign, but your narrative, the helicopter, the world map, they are all gone. Completed levels can be chosen freely.
You can play custom campaigns made by the community on steam. Also, you can download levels (.bfc) and place it in the "Level" folder. Then you can go to "Custom Campaign", offline, and play it. You can already create your levels and, if you want, share it (You have to finish your levels before sharing them to ensure fairness so don't create levels that were impossible to defeat).
A very hard varriant of the normal campaign. If you lose all lives you lose the entire campaign instead of given the chance to restart the level. Their description stated that Irobro hard is very hard to beat.