Lunatic mode ain't more hard, is strangely unfair, it takes away any invulnerability window and the same bullet takes all your lifes, ain't the same thing if you limit them to only 1?
other than that, mouse enemies are kinda hard to kill, but not a big menace, small bullet bomb mechanic is kinda nice, but it would be more interesting if there's one spellcard that backfires such ability, and turn very small bullets into bigger ones.