Location based or pervasive games are played outdoors from users with GPS enabled smartphone devices and involve physical visits of various geographical locations by the player. The fact that the playing area combines both the digital and the natural world, gives unique advantages to location based games that were explored by the relevant literature in domains such as: education, marketing etc. Furthermore, financial aspects cannot be overlooked, given the success of certain genre representatives in the gaming market, especially in the youth target group. However, developing such games is far from being trivial requiring high programming skills, while the administration overhead induced by large scale deployment is also an impediment. Motivated by the above, in this paper we present an overview of the system architecture and discuss design concepts of the GeoMakeIt! platform, which targets at facilitating location based game development by lowering the gap between the background of potential game creators and the programming skills required. Contrary to efforts existing in the literature that target at customizing specific game plots, the proposed platform is designed in an open ended manner to act as a marketplace of plugin components whose customization and synthesis can output diverse game experiences. As such, we envision that GeoMakeIt! can attract the interest of both experienced game developers and amateurs.