Here's what's new in version 1.7:
Optimized some laggy animations in EBF1, especially the final boss and glowing swords.
Optimized some laggy animations in EBF2, especially the Spirit foes and glowing swords.
Fixed a bug in EBF2 where the right difficulty was not set in the minigames selection.
(making getting the medals impossible in some cases)
Tried to fix possible Hydra softlock in EBF2, not sure if successful.
Added the Epic+, Epic++, and Epic+++ Difficulty options to EBF2, for people who want to suffer.
(no achievements for these)
Added the Physical Tank, Magic Tank, Careful Offence, Holy Quake, Giga Cleaver, The Plague, Solar Flare and Scholar upgrades to EBF2.
Gave Matt the Sniper upgrade that Natalie has, and buffed the effect of the Berzerker and Ready Edge upgrades.
Added 7 new achievements to EBF2.
Fixed a few achievement descriptions on Steam - they didn't mention which game they're from.
Fixed a few minor typos.

Stuff I will try to do soon:
Steam trading cards.
Optimize performance in Adventure Story and Bullet Heaven.
Add more prototypes, like the NPC builders.