I like this idea. It's great to see bunker functionality used in new ways.
There are two maps near the top of the U.S. custom list which both use bunker-tanks. Using this idea, however, is not enough to make something worth playing. It's a nice start, but it's not an entire map. Ultimate Tank Defense gets it. Bunker Circle Defense does not.
What do both maps have in common?
Both Tower (Tank) Defense maps allow the placement of units inside siege tanks. From inside, they can fire at enemy units while the tanks make good use of their arclite cannons.
Circle defense stops there and takes its place among the hoard of bromide TDs. There is no incentive to put units in tanks nor even to buy tanks, as the units do more damage once they're sufficiently upgraded. The map is won with a simple optimization equation:
((total dmg upgrades+1)*5 / 20 unit cost) > (# of units *5 / cost of upgrade) , build unit. Else save for upgrade.
Even with rough estimates, this is an easy map. Script a bot or conscript a toddler and afk for 30 minutes. Grats, you've won. There's really nothing else here. 3 unit types and 3 towers: 1 ground, 1 air, 1 both. Mix and match as you like. I was never even really sure what the conditions to lose were. One playthrough was enough for me.
Ultimate Tank Defense has been around longer and, consequently, has had more time to acquire polish. It shows. The older heroes are much better balanced than the new ones, and, though it's no epic, what's there makes sense. Units in tanks grant abilities and buffs to the tanks in addition to their own munitional contributions. Voila, reason to garrison them. Was that really so hard?
Ultimate Tank Defense is, however, by no means ultimate. It has a number of shortcomings which we hope shall be limited in future revisions. Certain new heroes *cough* Brutalisk *cough* tend to bring a lot more to the battlefield than others. Too, certain abilities granted by garrisoned units seem very weak. All that aside, the largest flaw this game suffers is horrendous performance. Framerates often dip and are drowned in single digits at around wave twelve. At that point, abilities can't be effectively used.
With so many barebones TDs around, it's easy to forget what this genre has to offer. While it's not yet Burbenog, Ultimate Tank Defense would be worth playing even if its position on the list didn't force one to play it.
While we hold out in anticipation of later versions, Bunker Circle Defense feels like an alpha of Ultimate Tank Def. Look to it as proof of the custom map system's failings, but don't mistake it for diverting: it's a distraction at best.
Ultimate Tank D 6/10
Bunker Circle D 2/10