I'll try and use an easy to read format as there is a lot I can say about this map from someone who is a big fan of multi-team Foundation, and as someone who used Foundation as their first map to remake in MCC. I'm approaching this imagining this map was designed for 8-players, since your description doesn't specify intended player count.

Comments

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• I like how you redesigned the structure that surrounds Energy Sword. Making it multi-level was a really nice touch to add verticality to the center while also improving the cover and movement options.
• I appreciate that the weapon spawns were mostly retained keeping it mostly identical to the original map
• Adding structures and objects to break up Foundation's notoriously long line of sights in order to break-up gameplay was a good idea
• Color palette used on objects was appropriate for the theme
• Some good ideas for movement options
• The geometry on the map looks very nice, this definitely looks and feels like Foundation at its core

Critique

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• Objects and geometry meant to break up lines of sight don't always do their job and aren't integrated well into the map. The triangle pieces where BR spawn feel odd and don't help to break up long range engagements due to the gap in them, and rather serve to only help cross-map engagements. The small crates placed behind turret platforms don't really do much due to the size of the walkways, and again only seem helpful in a cross-map engagement.
  
• For an 8-player map this map is huge and makes mid-to-close range weapons, like the Assault Rifle, look useless with long unobstructed lines of sight. Given that there only seems to be two Carbines and two Battle Rifles, grabbing those may be a greater priority than Shotguns or Energy Sword in Slayer game modes.
• Explosive barrels on the map look to be placed with purpose, but feel out of place sitting in the middle of rooms and hallways making them less threatening
• This map mostly feels unfinished and lacks polish. Rooms are hard to identify outside of the number labels, the map feels empty due to the size, and some geometry feels like its only purpose is to provide cover, like the pillars covering each staircase under BR platform.
• This map doesn't make full use of the Halo 5 movement features as many movement options aren't realized and it doesn't feel like the map was created in mind for anything besides clamber.
• There are a lot of floating pieces, gaps between objects, and merged objects that have textures flickering
• If this was intended to be a remake that was scaled up, and not a "re-imagining," there are multiple inconsistencies in terms of sight lines, most notably with the doorways to the four rooms on the outside of the map. In the original Foundation, the entryways to the rooms were mostly obstructed by the large trapezoid-shaped pillars in front of the door and the only thing a player from another room could see was the far end of the door jam forcing players up to the door. From BR platform a player can see pretty far into the rooms (to the back wall almost), which could lead to spawn camping issues.

Quick Notes

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• I don't think Strongholds work right now as when I tried to boot up the game in Custom Games it wouldn't load, but could have been a server issue
• The Rocket Launchers are fully loaded, instead of just having two rounds like in the original Foundation. Is this intentional?
• The original had Warthogs and Spectres, but this version lacks vehicles entirely. The wide spaces here could make vehicles on the map fun.
• The intro cameras don't showcase the map when the match begins

I haven't gotten a lobby together to give this a good playtest, but if I were to rate it as an 8-player map right now it would lean on 2/5 stars. As a BTB map it could become a 3/5 if some vehicles were added and more lower-tier weapons were added to its current state. This map is Foundation at its core but is lacking in terms of visual appeal, movement options, and thoughtfully created sight lines. If you wanted to really step up this map I'd recommended creating a clear goal on what you want this map to accomplish and work with that in mind. For example, do you want it to be a faithful remake or a re-imagined BTB version? Currently, this map seems to teeter between these two conflicting goals.