You can now spend your coins on upgrading Nax. There are a variety of things you can upgrade.
Health and Mana will increase Nax's max HP/MP, which is handy if you're having trouble. MP doesn't actually do anything yet, but a magic system will soon be implemented which will expand combat options at the cost of MP.
You can also upgrade weapons. Upgrading weapons grants new attacks. In the first demo, all the attacks were unlocked, but now you'll have to buy them. Each weapon will come with the main combo, air attack and the back attack (lock+back+attack) unlocked from the get go. While the rest of the attacks can be unlocked. This includes the forward attack (lock+forward+attack) and the super attack (block+attack). Each super attack will have three levels of upgrades. Here's the upgrade tiers of the Redband and Tesla Whip weapons.
REDBANDStart: Combo(attack, attack, attack), Spin Combo(attack, wait, attack, attack), Splitter(air + attack), Launcher(lock+back+attack),
Level 1: Unlock Stinger (lock+forward+attack)
Level 2: Unlock Crawler (block+attack[hold])
Level 3: Unlock Million-Stab Combo (attack, attack, wait, attack[mash])
Level 4: Crawler L2
Level 5: Unlock Roundtrip (attack[hold]
Level 6: Crawler L3
TESLA WHIPSStart: Combo, Tesla Arc(lock+back+attack), Tesla Air(air+attack)
Level 1: Unlock Tesla Storm L1 (block+attack)
Level 2: Unlock Tesla Slam (lock+forward+attack)
Level 3: Tesla Storm L2
Level 4: Tesla Bombs (passive ability, adds an explosion to the end of the Arc, and Slam attacks)
Level 5: Tesla Storm L3
*all other sub-weapons will follow this pattern.
There are other things that can be upgraded, like item slots and wallet limit. The snatcher's range also increases as you upgrade it.
This store gives a nice sense of progression and also makes the game easier to get to grips with, as you aren't overloaded with potential attacks.