The game is available at the following link:

https://dosgames.com/game/space-chase-part-one-city-under-siege

Not sure if the game is abandonware entirely so I only put a link to the first shareware episode. But the others are also around online.

You can glitch through pretty much everything in this game. Episode 1 could be done a lot faster if there is a way to get an out of bounds exit in the final level, which I didn´t find when playing around. So you have to play through the last level normally more or less, apart from the last bit of the level to reach the exit sign. Sub 5 is easily possible. The game goes faster when you disable the sound but its also harder to get through the walls then.

Time starts as soon as you move in the first level and ends as soon as the final screen comes up.

CPU cycles full