First of all, I know that most of these things are easier said than done, keep that in mind.
Secondly, I'm not an expert in game development, I'm just using my common sense to try and give the devs some tips.
So let's begin, shall we?
1. Hire some experienced developers.
I think that this is vital to the game, given that it is barely playable at the moment, needless to say that there are many gamebreaking bugs that make the game unplayable (I can't even join rooms rofl).
2. Market the game (properly).
Another vital part of making a game is advertising it properly. I think investing in some ads would be the go-to method. Also, am I the only one who remembers that S4 League actually used to have ads on TV and stuff?
3. Involve the community.
I think that this isn't only a way to get more content (by making costume creation contests, for example), but also a way to acknowledge the fact that there are talented people in our community that can improve the game tremendously. Did I mention that it is FREE?
4. Add some easter eggs/references
Maybe I'm the only one who values easter eggs in my games, but I'm still going to put it on the list. When I say easter eggs, I think of wearable items, like a Hatsune Miku hairstyle or something like this.
5. Remove/improve small details that ruin the game experience.
-The first thing a player sees is the GUI, so let's begin with this one. It's horrible...no, really, there's really nothing else to say. The colour combo between blue and orange does not match the aesthetic of the game IMO, needless to say that it's an eyesore. I think reverting it to the previous one would be a start, I think anything is better than the one we have now.
-Item descriptions. There are just so many descriptions that don't even make sense. The most ridiculous example would be the Frying Storm Bat: "If use this Weapon, You Can Feeling power and strength!". There are more awkward descriptions, but for me, this one takes the cake.
-Item names. They fall under the same umbrella as the previous topic (descriptions). They're generally typos, or weirdly spelled words.
To both of these, I'd be more than happy to tweak/rewrite some of them *wink* (it's not like I have anything better to do anyway).