The costume slots are free (a nice handout to players) but the weapon/trinket upgrade slots are only temporary and pretty costly. It feels kind of backwards for me, in that aesthetic choices are generally reserved for the paying portion of free to play games while something like weapon slot upgrades or trinket upgrades would be something you came across by delving deep enough into the game. Not that spiral knights should imitate every other F2P game, that's just an observation.
What I feel would be more feasible in three rings would be to make the temporary slot increases cost either crowns or a smaller number of energy, and have a higher cost for unlocking them permanently. This would let someone try out the slots to see if they were really all that better while also making more people fork over the higher cost for the permanent unlock. If they could be unlocked permanently I'd buy the slot increases today (or at least over the course of the next few months or so). Until then I can't rationalize buying the temporary increases.
also I'd charge to unlock the extra costume slots but that's just me.
I've played a lot of F2P games and I'm enjoying spiral knights, or at least what I've played through thus far. I've only spent 5 bucks on energy but I'll probably spend more in the future.
I wouldnt mind seeing a permanent unlock option. however, the weapon/trinket unlocks are an energy sink. The current prices of 150 (trinket) and 250 (weapon) are not much for 30 days, considering that will only get you enough clockwork levels for a day to a week, depending on how often you run.
What price would you expect to see these unlocks for if a permanent option existed?
250 * 2 (2 weapon) * 12 months is 6,000. This is for 1 year. Would you pay 8,000 - 10,000 for permanent unlock of weapon?
150 * 2 (2 trinket) * 12 months is 3,600. This is for 1 year. Would you pay 5,000 - 8,000 for permanent unlock of trinket?