I only play one type of game. It is called a real time strategy game and there is one company that makes them, Blizzard. Every other attempt at a real time strategy game fails.
Adjustable commands for unit groups. This is basically a slider whereby you can set how aggressive your group is. A highly aggressive group would attack anything that is near. A fearful group would flee. Every unit should have artificial intelligence 'quick' settings like on a grid. This would allow you to concentrate less on micro managing units and more on strategy. An example would be highlighting a group of soldiers and dragging their aggressive level down. When an enemy approaches they will retreat rather than run to their death. This would also be helpful if you set a unit on patrol. If it found something then it wouldn't automatically engage. The unit should be able to asses it's odds and act according to it's aggressiveness setting.
Interactive Terrain on Three Dimensions. One of the most impressive feats of gaming I have seen is the underground pipe system of SimCity 2000. Being able to build and interact with what is happening underground in real time is something that could easily be applied to a real time strategy game. A player might be building a tunnel under the enemy base while he is distracting his opponent elsewhere. The applications for underground development are endless. Also In-Game Modification of the Terrain where a player might build a wall or dig a trench would also create new elements of strategy. Being able to destroy any element on the map or change the elevation of the map might be interesting and is definitely something that belongs in war simulation. The idea of a map being completely different after a battle should not be unheard of. Special crews might be able to modify terrain like diggers.
6 years ago