How do I simulate "filling water" in Game Engine I'd like to make a mini game where the player would have a water tank being filled and it has an outflow where he controls. He will be able of increase or decrease the amount of water coming out of the tank. How can I do it?
I'm new in Blender and I made a water simulation of this tank being filled as animation, but I couldn't apply this to the game engine.
If you, guys, could give me a light, I'll be thankful.
Possible duplicate of this post. What you're trying to do is something not currently possible in vanilla Blender at runtime. 

My advise is to fake it with different planes, particles, etc. but you have to learn Python to do this, and it will require a lot of work. Realtime simulations are demanding on your system, so even if you pull off full water simulation in Blender, 99% of everyone with a personal computer won't be able to run it.

So make a plane as your water surface, apply an animated texture to it, and animate the mesh itself. This way you'll at least have a water surface. For the inflow/outflow, make properties stating the water level. Animate this with two keyframes and let it cycle the values between 1 and 0 to make the water rise and fall. Animate some cylinders with the same process as the water surface so it looks like it's pouring out of something. 

Remember, with any and every game, keep your polycount as low as you can. Running a water simulation at runtime will blow your polycount to the roof, and lag, or even crash on most systems. 

Hope this helps.