What plug-in do I need to play Spiral Knights

What I've been able to determine so far

• There are no explicit classes in the game, it is solely based on your gear.
• There are three types of weapons in the game: sword, gun, and bomb. Characters have all 3 types, but may focus on upgrading one type over the others.
• There doesn't appear to be any healing or support type items, everything is either about doing damage to enemies, or preventing damage to yourself.

Since you can purchase crystal energy with the in-game currency, it seems like kind of a moot point. There are times where you will need more than 100 energy, for crafting or such. Now you could choose to just not do this, and then you wouldn't need crystal energy. But you can also choose to go farm some crowns, then buy the crystal energy that you need.

So you can certainly get through the game without ever spending real money, and if you aren't spending real money, you should just look at crystal energy as another in-game resource which you occasionally need to replenish with crowns.