Right now the game is being tested in sort of a closed alpha/beta to work out as many bugs and errors as possible. The focus right now is on the custom ships and the Steam Workshop. So far everything works as intended. You can import and upload your own ships to the workshop. Subscribe to ships from the workshop. At the moment it just uploads whatever is in the folder that your ship is in, so that may need to be changed before releasing the game.
After the game is released the new focus will be shifted to adding new abilities, weapons and/or enemies. The menu navigation will also have to be updated to work better with gamepads (ex. sometimes no UI elements will be selected which means that you'll no longer be able to use the gamepad to navigate through the menus!).
As for multiplayer... It will be attempted to be added. Multiplayer coding can make game development wayyyy harder. Sure the game would be soooo much more fun with others helping fight off baddies but now all abilities, enemies and menus will have to be changed to work properly with multiplayer in mind. One particular problem I have in mind that might make things difficult is... what happens if a player disconnects for whatever reason? Should the player be allowed to join back? If so, do their stats get saved or do they start back at level 1? Yea... there's so much more to think about if the game is multiplayer. But hey, it'll at least be attempted! If it turns out to be too big of a pain to implement right now, then it'll either be saved till later or just scrapped all together.