I will let you decide on what you want to work on next for your dungeon theme. I like having creatures and the Wizard.
I admit, I am trying to wrap my head around how one would show other weapons and armor on the paladin programmically. To me a lot of drawing would be required, because of the different directions of the character and unique animated movements.
That is probably why I am leaning to work with your space theme first as I would just need to rotate a weapon and I am currently working on a game that uses the 360 degree gun rotation.
For your question on the space theme, I am a little biased at this point.
1) I plan to use my own hero that only has a side view sprite which would work OK with most of the smaller robots that only have side views too.
2) I am using a 360 rotating gun which works fine for a side-view sprite (as well as for many of the robots), but would require changes if I had the move the gun behind the player for a back view (which I am sure I could figure out but was not planning for).
3) Since they are robots, I think it is OK to just have the side view sprites, but must admit that 4-way movement for the larger rocket firing robots might look better.
4) I was planning to use the larger robots with a side scroller view if I thought they did not work well enough with their 2 directions.
5) I have other character assets I want to have in the game too and they are only 2 way as well.
So for me, I would lean towards more environmental assets. Having more of the other environmental assets would help make the world feel more “believable/lived in” and allow more for a variety of levels.
I am going to try to design the enemies to support 4-way animations though, so that if you do 4 (or 8 way), I can support the 4 way.
Is the 8 way movement to benifit shooting in more directions or just to have the character transitions smoother for turns/directions?