A very well made incremental. I think this game would sell well if made into a full one and uploaded to steam!
Some notes if you are planning to update/make a full game out of this.
1. There is a strong need for juice/game feel.
- Camera shakes on hitting enemies/shooting big projectiles
- Sword spinning sound that is pitched by how fast the sword is spinning
- Hitting enemies sounds and particles
2. The end became too grindy and I didn't feel the upgrades doing anything that much better at the end. Though at the start, it was a very good progression, where after each run I wanted to go another one and buy more upgrades. So for the end it needs rebalancing in my opinion.
3. The power fantasy (getting stronger and bigger) is good, but it could be even better.
- Let the player upgrade the sword size to a level where it is big enough to reach all the corners of the map while sitting in the middle. Then you could introduce a new mechanic, where at certain moment in the game, the map becomes bigger, and now you are not fighting little enemies, but big monsters. Makes the game really expandable
- Give a player another sword in another hand, which will be in opposite side of current blade, and let it be upgradable, so in the end the player could have just 15 blades sticking out of him, eventually becoming a beyblade :d
- Add shockwaves (not the current one in the game, although that one also works). If the sword spins fast enough, add shockwave around the sword that just flies towards the edges of the screen (smilar on how you drop something in the water, and the ripples just away from the point of impact) . With the right effect, this would make game feel a lot better. Also that shockwave could do the same stuff as the sword (deal damage, burn them).
- In the end add unlockable upgrade, where the player no longer needs to spin the mouse for the sword to spin, he needs only to hold left click. With this, the sword could reach ridiculous spinning speeds ( which again can make the game feel really good with certain effects. Similar to how stylized games handle fast spinning objects, like helicopter blades, where they add circular white lines). But add this upgrade only at the end, as this defeats the whole game idea of spinning manually.
4. The game needs purpose. Currently there is no telling why we killing these monsters, and what is the end goal. The end goal could even be to kill all the bosses at once, like in secret boss stage. But there is a need that someone would tell the player that - your camp has been overrun by monsters, and you need to kill these seven lords to stop them (or something like that :d)