v1.1 is now live on the main branch. I decided to up the version number to v1.1 since this added a few features and is not just bug/balance fixes.
Edit: There was an issue with pressure mode unlocks in v1.1.0. Please make sure you have v1.1.1 which fixes this issue.
So what’s in 1.1?
Pressure (difficulty) levels

After beating the wave 5 boss for the first time, pressure levels will be unlocked. These are a cumulative set of modifiers to make the game more difficult. You must beat the last boss on the highest unlocked pressure level to unlock the next one. There is a new menu after clicking New Game where you can select a difficulty level.
If you just want to jump to the highest difficulty right away, there is a button in the settings menu to simply unlock all difficulty levels.

Endless Mode

After beating the last boss, you will have the option to continue playing in endless mode. In endless mode, previous waves will be repeated, but enemy health and DPS will increase in a somewhat linear fashion. Additionally, some global buffs will be applied as you continue through the wave which will make enemies resistant to certain forms of attack.
Can you beat the new boss at the end of wave 8?
Combat Timing
(I’ll admit, these changes get into some real nitty-gritty details, so feel free to skip it if your eyes start to glaze over. The TL:DR is that I fixed several issues which were causing combat outcomes to vary based on game speed.)
v1.1 includes an overhaul to how combat actions are executed.
Previously, if multiple actions occurred on the same frame, the order in which they were processed was deterministic, but not predictable. With 1.1, all actions are timestamped based on when they should have occurred as if the game was running at an infinite frame rate. If multiple actions trigger on the same frame, the one that should have happened earlier in time is processed first.
This change eliminates some corner cases where changing the game speed resulted in a different combat outcome. I also fixed a bug where the enemies’ initial delay was not being scaled properly to account for the game speed. This meant the game was easier at 4x speed because enemies would not start acting for a significant amount of relative time. Hopefully, now you should get the same results no matter which game speed you are using.
The action ordering is most visible to the player when there are multiple tiles that precharge more than 100%. Previously, there was no way for the player to determine which tile would trigger first. This can be relevant if you are trying to line up buffs like Fired Up or debuffs like Vulnerable. Now, tiles that precharge for an amount of time greater than their charge time will trigger based on which tile has the greatest amount of “extra” precharge time. For example, consider these two tiles:
Fireworks: Charge time 8s, precharge 12s = 4s of extra precharge
Rain with a 50% precharge mod: Charge Time 5s, precharge 5.5s = 0.5s of extra precharge
In this case, Fireworks will trigger first, followed by Rain. Both will occur after start of combat tiles and before any tile with less than 100% precharge.
I have also changed the way flat precharge time (i.e. seconds) interact with changes to a tile’s charge time. Previously, the tiles base charge time was used to calculate its initial charge percentage. This resulted in confusing interactions and misleading tooltip values related to precharge.
Now, the tile’s modified charge time will be used when calculating a tile’s initial charge at the start of combat. This means that tiles with a high amount of flat precharge time will benefit greatly from an increased charge rate (I'm looking at you: Fireworks).

Full patch notes:
(Note that many of these changes were present in the beta branch, so this list may look familiar)
Features
Added unlockable difficulty (pressure) levels
Added endless waves after the wave 5 boss.
Added new boss fight for endless wave 8
UI Updates
Enemy UI intent values now dynamically scale based on their current buffs/debuffs and difficulty scaling. It currently does not reflect buffs the player may have (e.g. Chrysalis or Vulnerable).
Added overall damage stats to the Victory/Defeat screen.
Added combat time and DPS to the per-fight stats pane at the end of the fight.
Damage types are now sorted from largest to smallest in the stats pane.
Tooltips of tiles in the inventory should now always be fully visible. In general, they should behave much more closely to tooltips outside of the inventory.
Balance
Increased Hail’s damage from 3 to 4.
This is intended to help snipe the back line, but its base damage was too far below the curve to feel meaningful.
Replaced one of the Cats in Wave 1 Fight 3 with a Weenie
The increased enemy health and DPS in this fight often resulted in a lot of damage taken.
Replace one of the Ghosts in encounter 23 with an Imp.
The DPS of this encounter was way above the intended curve.
Molten Blade now pierces all defenses (shield, ethereal, stoneskin). This has the side effect that poison now also pierces all defenses. Also, a new piercing mod has been added.
I wanted another option to deal with ghosts and stoneskin enemies.
Increased Mage Cat’s charge time from 5 to 6.
Reduced Knight’s enrage damage from 6DPS to 5DPS
Increase Cat Druid’s cleanse period from 2s to 2.5s
Reduced Ghost’s base HP from 50 to 45
Reduce Giant Hat’s attack period from 2 to 1.75 for its first four actions (before the bit hits)
Scavenging for pipes in the workshop will now always provide either a T-pipe or + pipe. There is also a 35% chance of receiving a bonus underground pipe.
I got annoyed when I just needed a new T-pipe to connect a tile in my inventory, but got an underground instead.
The precharge calculation now uses the modified charge period when calculating the initial charge.
Previously, the initial charge calculation used the tile’s base period value, which resulting in confusing behavior and misleading tooltips.
Increased the Precharge 2s mod to Precharge 3s
Flame Ring’s Fired-Up buff now increases based on the number of adjacent powered tiles.
Flame Ring’s damage was useful for early, short fights (10s or less), but it quickly became less useful in later encounters. This should naturally get more valuable as the grid fills up and can work well with the precharge change.
Mods can now be applied to tiles that have only start-of-combat actions (e.g. Quicksand and Power Tea)
Only mods that make sense are allowed; you can’t add a charge speed mod to Quicksand or a vulnerable mod to Power Tea.
Bug fixes
Fixed a bug in the enemy UI where a negative attack value would be shown if there was enough negative strength.
Game speed is now properly applied to the initial enemy delay at the start of each fight. (This effectively buffs all enemies if you have been playing at 4x speed)
Reworked how combat actions are processed to eliminate some corner cases where different game speeds resulted in different combat outcomes.
The grid for the Customize workshop tool has been increased from 5x6 to 6x6 so that Cooling System will fit when placed horizontally.
Fixed the mod validation logic to prevent activating mods that do nothing. New error messages will be shown.
For example, connecting Doublestack to a tile that applies no buff or connecting +2 Damage mod to a tile that does no direct damage will now show an error.
