I didn't have high expectations going into trying out gd_obelisk, with no posted images it was hard to really expect anything at all really.
First impression was difficult, as I had to generate the nav mesh myself since it didn't seem to be included. One nav_generate later I found myself attempting the first wave.
This map has an INTENSE amount of creativity, imagination, and spirit put into it. Wandering around the map I thought I had a good idea of the dynamic element: the Obelisk of mini-crits, imagine my surprise when at the start of the first wave there was another dynamic element, then after the first point was capped another, and at the start of the second wave there was yet another!
I won't go into detail the amount of dynamic creative mechanics put into this map, but I will breifly mention that the effects of the wave are not something solely felt by the player, taking a chaotic environmental variable and turning it sideways to fight for you rather than against you was a remarkably satisfying feeling.
Regarding the Obelisk, I think it creates a very intresting risk/reward dynamic were before the next group of bots comes, I'm tempted to just get in reach to get an extra minicrit shot or two off, or as an engie I'm tempted to see how far I can try to get to boost my sentries damage.
Wave 1: I love the themeing, but I'd consider slowing everything down, its very brutal to have so many bots come at once, consider reducing the move speed of the bots to 50-70% of their normal move speed. Also giants notably get stuck on the bridge ceiling at the right spawn (facing bots from point)
Wave 2: Reflect pyros are a soldier and even engie's worst nightmare, try to make these pyros alwaysfire and in general this early on (with this little money) consider making damage 33% of normal for all projectile/hitscan. Also same movement changes as above
--- Beyond this point I don't feel comfortable give wave specific advice, as I admittedly cheated to get further (testing solo has its limitations) --
Wave 4: Let me just say that the dynamic element on this wave creating a 3-way battle was something that reminded me of half life and sent chills down my spine.
Point Blocking: I think blocking the point would be a really nice way to give players a way to counteract losing the first point, in duos it also tends to lead to clutch moments where one player stalls just long enough for another player to make it in time.
Closing Upgrades: I think closing upgrade booths mid wave remove players abilities to do cool last minute plays or salvages, I'd recommend keeping the booth in spawn open full time.
Money collection: Every robot dropping money is really brutal, if you don't want to go with an auto-collected money idea, perhaps limit money drops to giants only, a fair-ish compromise that may help duos without a money collecter get through.
In general I'd era for balance on the side of caution toward the players, having to fight a wave and a map can feel brutal, but mechanics that can help the players if they are clever (more like wave 2) are especially fun to play with.
Very interesting fun map, I'd love to see where it goes from where it is now and would love to play it again with some balance changes.