Right now the game spawns the enemies at the available spawn point furthest away from the player (all of which are manually placed). It does this for several reasons:
- To avoid spawning enemies right beside the player. It's no fun having a Titan materialize within slapping distance, and it looks weird too.
- To add a little breathing room between the enemy dying and a new one replacing it. Some battles also have a longer delay between enemy spawns for this same reason.
- To give the enemies an opportunity to flank the player, preventing them from just sitting in one place. The game doesn't try to spawn them right behind you, instead enemies may try different routes to reach you as the battle goes on.
Unfortunately I can't really change the spawning system as the whole game was already balanced around how it currently works. However, if I ever get the chance to make a sequel I do plan on trying different new spawning systems, including a more traditional wave setup. In fact, Rebel Ops already played a bit with this idea in a few missions.