After about 3 hours I finally have come up with a concept that is I can build within the time that ludum dare allows.

Graphical style: steampunk

Viewpoint: 2.5 sidescroller

Concept: Basically the player is an airship with several “attractors”. When the player destroys an enemy they can use the attractors to attract the parts (or all) of the destroyed enemy. Parts can be shot off by enemies , also some may help (extra weapons)or hinder(explosives) the player. Eventually the player “evolves” by attracting all the parts of destroyed enemies.