Swiv was one of the best shooters I had played on the good ‘ol Amiga back in the day. I loved its detailed & varied levels, the numerous enemy waves and the imposing laser beams of the bosses.
However, what I found very noticeable & interesting, were the Crop Circles left behind by an indestructible weird looking ship, as it flew away at the waste-lands in level 2.
This ship was completely different to any other you encounter in the game and its Alien-look & orientation is evident, leaving a direct innuendo of the “origins” of the crop-circles on earth.







Interestingly it looked very similar to the actual crop-circles scattered around the world:

The following look ideal for shoot em ups...
This one in particular looks similar to the one in Swiv:



This looks exactly like the ship sprite from Crisis Zone on the NES!





And doesn’t this remind you of the enemy waves in Project X on the AMIGA?







So it would seem that many Shoot Em Up artists were influenced by the crop-circles and their mysterious sci-fi themes after all!