Hey, JumpScape is not finished yet but i want to annouce mod tools for that game. Probably your question is "what can i change or add?", thats a good question, for now im sure that you will be able to: make new maps, new campaigns, new models, new materials, new animations and ability to change game rules. I am also thinking about releasing big part of source code which will let you to modify menus and other aspects of the game. Maybe your second question is "why you want to give mod tools?", well i am also modder and mapper and after lack of Infinity Ward's support i've decided to make this game and my idea is "game from modders for modders".
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I am glad to hear that. I can't wait until first release.