Allright... I've now officially given up on the 100,000,000 combo Quest!! I played the game for over an hour and reached 2 million combo with turtle flows of 305, 200 and 200, a filled ceiling of lasers, a ground filled with buzz saws and machine guns, the middle filled with bumpers and the biggest mega hammer...
Calculation would then show that, in order to reach the 100M Quest, I would need to let the game run for a least another 50 hours... ... (O.O) ... WUT?!?!?! ... forget it! This one shouldn't be labeled "Hard" but "Impossible"! =(