After all these years, and growing up with Windows 3.1, I have seen an entire evolution of computers and software. Touch screens and large resolutions were a pipe dream just 15 years ago. Now it's the norm. Going from a Packard Bell (yes, before HP) that couldn't run 3D Ultra Mini...
The timer is your biggest enemy. Get the high scores by finishing levels as quickly as possible.
That said, you don't die if the timer runs out. You just lose points.
You might have to backtrack to find all the coins.