I use the infinite continues cheat. It doesn't mitigate the difficulty any, just the repetition.

I owned the PS1 version of this game in my younger days (and I probably still do). I remember certain levels where I spent days, sometimes weeks, playing them and reloading until I was finally able to beat them. Now I can beat the game in a day with 40 lives to spare.

The real issue with the game is the view distance, it's way too short.
I wish there was a mod to fix that.

Not really that hard.. took my about 1 hour each map. depending on lenght. Hardest level is imo the last in picture city, this one exactly - /watch?v=WfROVuGkjCE .. I was stuck about a few days here.. it requires a lot of preciseness.