My previous game, The One Who Struggles, had an alt-fire mechanic for each weapon. I really like the variety of strategy it allowed. Like the rapid fire weapon, Thorn, had a shotgun alt-fire, so you could run up and deal massive damage to the boss before it entered its invincible phase. I would purposefully design situations of the game so each of the different weapons and their alt-fires were useful.
For my next game I was thinking of having a similar system. However, you'll be able to freely aim in 7 directions on the ground and 8 in the air in that game. This limits the types of alt-fires I can put in. All the sudden one that shoots at a different angle isn't as practical since you just aim. There's also the nature of the weapons for this new game. They're very different. It's an interesting problem that I'm excited to solve to be honest.
Hopefully I'll have something to show in a few weeks. I haven't made time to actually program stuff really. This idea was also not part of the original idea so it's a bit of feature creep. Still it's not too bad as I've made the system before.