I have 2 ways to build a brick tower, and that is to make a cylinder and applying textures and bump maps or create the bricks separately and make it as one mesh. Which would be best for a game engine? , I think creating the bricks separately would consume a lot of memory especially if I have these towers in one area(not 100% sure)
You're right. Texturing a single mesh is better. You could also use bricks and replicate them with the Array modifier, so they are linked copies (until you apply the modifier) of the first. But texturing remains the lightest solution, I think.