Had another few goes on this today. It still isn’t much easier! Managed to complete 500m, but only because I bought a “one hit shield” item. Having said that, I had a life spare at the bottom so I could have done it. Unlocked Puchi as a result, and completed 300m with him. Also had a go at Pressure Driller mode, which is even more frantic than Mission Driller. Managed to defeat the 200 ton baddie, and nearly got past the 300 ton one, but died. Again.