I've been sitting on this idea for a mod for BTD6 (or even a potential idea for BTD7) for a while, and I figured now would be the best time to reveal it and talk about it.
I call it Crosspath Chaos.
The rules and mechanics of this mod are simple: ALL upgrades and crosspaths are open to purchase at all times, regardless of which upgrades have been bought prior. In other words, even if you have already purchased an upgrade on two separate upgrade paths, you can still purchase the an upgrade on the remaining upgrade path.
There's just one catch: you can only buy 6 upgrades at any given time!
Allow me to give you some examples of what this means and how this would work:
- For Tier 1 and 2 upgrades, you are able to purchase any and/or all of at will as long as you haven't reached the upgrade limit. For instance, you can have a 2-2-2 Glue Gunner that can apply corrosive glue to multiple Bloons at once that also move really slowly. Or maybe a 2-2-2 Sniper Monkey that can fire quickly, do 7 layers of damage, detect camo and even launch shrapnel!
- With Tier 3 upgrades, much the same rules as with the Tier 1 and 2 upgrades apply here. So you can have a 1-3-2 Bomber Ace or a 1-2-3 Crossbow...
But what you can ALSO do is purchase TWO Tier 3 upgrades from TWO different crosspaths. With this, the combinations you can generate end up being dangerously effective! Take, for instance, a 3-0-3 Super Monkey - that's a Sun Avatar crossed with a Dark Knight; basically a budget Dark Champion!
- Tier 4 upgrades are mostly unchanged from how they are, except you can opt to purchase either BOTH Tier 1 upgrades for the tower or just focus on both upgrades in a separate upgrade path. So while you can still have your 4-0-2/4-2-0 Arcane Spike Wizard, you can also go for a 4-1-1 Arcane Spike Wizard that fires high pierce bolts and fireballs.
- Tier 5 is almost exactly the same as it is in the standard game... except that you can ONLY purchase this upgrade if with one other additional upgrade. This, unfortunately, nerfs a lot of Tier 5 towers. Instead of your standard 2-0-5 Sub Commander, you can only have 1-0-5... or maybe 0-1-5 would be better.
That's basically the sum of what the mod would allow. It essentially allows for more diverse and creative crosspaths and potentially really powerful combinations.
Give it some though, and maybe think about what potential crosspaths you reckon could be good/fun to play with!