[Suicide Junkie]

I agree with Fyron that mines need some work. First of all, early in the game, it seems as if mines destroy every ship that is hit. Should this be so? Perhaps 1 mine = 1 dead ship is a bit too much. Late in the game, you just make sure you have enough minesweepers to sweep a maximum mine field and it becomes academic. Neither situation is 'fun', but rather seem to be doors with 'secret knocks' that once the 'knock' is known, just become a nuisance.

One thing to do is to remove sweepers from the game.
Then decrease the power of mines significantly.

A single ship still won't make it, but a modest fleet will have most of its ships take some non-fatal damage.
This will either slow them down to a sector or two per turn while they repair, or cause them to start taking losses and be very vulnerable to counter attack.