Actually achievable new game mode.

[Bobo]

I understand what Woody is proposing is not just multiple enemies spawns (we already have 2 on some maps) but it involves the necessity to defend from different directions with the use of multiple cades. Which leads to higher difficulty since you need to build 2 or 3 cades using cades brought by players, means a single cade would be weaker. In addition you'd need some more tacticts to build the cades properly e.g. you'd need a strong cade in the southern corner for wave 12 but no more in this spot for any subsequent waves, while you'd need the strong cade for wave 15 in the north...

I'd say the idea might work to make something interesting.

PS. what about a game mode where you have no cades at all?