Hey, what do you know... I'm planning on making a game that Ill actually finish and release sometime.
I actually prototyped this game 4 years ago in SGDK1, its original name was Ballio. I decided to recreate it from scratch in SGDK2. Total time worked on... Id say 2-3 weeks exactly.
Its still developing, but I finally have enough to at least show. Its called Neuro, its an OpenWorld Game about 2 Robots with the Power of Alchemy, crash landed on an unknown planet, seeking information to help them uncover their purpose of existance. Its a fairly complex engine, with every item in game being fused with or having the ability to be used with other Items. A Block based System, Similar to Minecraft.
http://www.youtube.com/watch?v=a8kpm_DRp2U&feature=relatedThat video demonstrates how the quick fusion engine works, You can ping(retrieve with a beacon) any item with a hardness of less than 4.5 and hold it in the first robot's gravosphere. Any Item held can be replaced anywhere else or can be combined with another item. Hence the name fusion. Sand + Topsoil = Peat (Flammable Grass) - Sand + Soil = Fresh Soil (FarmLand) I plan on adding 300 items.
Sprites/Lifeforms can also be created, and some fused items are Terminal- They cannot be fused with anything else.
http://www.youtube.com/watch?v=3NPPQcPWJfU&feature=relatedThat video demonstrates the physics of Liquids- In this case water. If Water is placed, it acts like a single glob, and disappears when hitting the ground. If water is placed in a porous block, (Sponge, Perlite, etc) It flows out of the block until the water runs out. This can be used to stop fires, and make makeshift ladders.
http://www.youtube.com/watch?v=ZyQhVmm5ZkMThat video demonstrates the daytime/nightime engine, at 100x speed. Daytime lasts about 7 minutes, Sunset about 2, Night about 7:20, Sunrise about 2:10. Different Sprites spawn at different times of day, with helpful (Health Giving Sprites) spawning at sunrise and sunset. Music Plays at Random Times, (Really Random) as to not get annoying. The only 2 Special Time States Implemented are Plenilunium, Night of the Blue Moon, (Increased Enemy Spawn Rates IN and OUT of Houses and Caves, and Solis ardoribus, The Day of The Burning Sun. Damage is caused if the player is outside, from the Heat of the Burning Sun.
Multiplayer WILL be implemented, I guarantee that. I would just like some suggestions that would make this game more fun, attractive, unique. Any ideas, or even criticisms. Anything that might actually help me develop this game more.

Currently, Im working on the Inventory Fusion. (Just random)
Edit: Life giving sprites now spawn at night, giving motivation to go out during nightime