I suggest improving the game

"this game are on alpha phase."
I have experience in game design, and based on this I can give advice.
Now you do not need to add new items, you need to expand the functionality of the already created one.
Otherwise, you will drown in details and miss the chance to develop the game, since there is always competition and, having interested people in an interesting beginning, you can lose this interest if it is not supported on time.
The first place in importance is to make a more interesting map, give up linearity, make a mesh of transitions if you find it difficult to make a map from solid polygons.
Solve the problem of depletion of resources or according to my proposed scheme for creating mines that extract resources to a warehouse from the time the player or AI control the object (warzone 2100) or otherwise.
In second place is the elaboration of storylines and quests with a non-linear plot tree.
Already these two points will help you get out of the arcade and make the game more complete.
In third place, I recommend making the ships moveable on the location map and redoing the combat mechanics according to the scheme I proposed in the first comment.
In fourth place, add the construction of mines and stations on asteroids, and make landings on the locations of the planets, where it will be possible to realize the advantages of long-range weapons over melee weapons (while battles are only on ships, there is little sense in a variety of weapons, since the battlefield is almost the same) ...
Take the example of chess, it is not so important to add new types of pieces to the board, how to think over the rules of moves of what is already there, there is one unit in checkers, but the game is eternal, draw conclusions from this.
I've seen three good game projects so far that have been killed by developers choosing to make items instead of gameplay, and this was a clear mistake.
Better a more developed gameplay with a small number of items and units than a sea of items and units with unfinished gameplay, I hope you understand this.
Better to make good chess than bad lego.