If you're stuck on level 68 and want a hint or two

[RevengeFromMars]

There's already another post which just shows the solution to 68 but I didn't want to be given the answer, I just needed a hint. Once my brain finally cooperated, I eventually realized that you can slide the red cube that's on the H-pattern. I was initially thinking it had to be destroyed, then I could slide something else there. Wrong, you can slide it just like any other item. I doubt this part is a spoiler, but you have to take out all 3 red cubes with the first ball (directly and indirectly). The white ball is needed to take out one final piece. And obviously, the final piece is not red but black. White can't directly destroy black so... (hopefully that's enough of a final hint)