Thre're 15 missions, with 3 difficulties. Average length is about 10 minutes. But, higher tier weapons make it faster.
There're 4 Armors which each level up independently. EXP is based solely on score, which seems to average 2-3k for normal missions, and 5-7k for Hard. First three levels come quickly, but after that can take upward of ten missions to level again. Normal only lets you level to 5, Hard to 7, and Inferno 8.
Level 1 weapons are atrocious.
The boss-type enemies show up more often than I recall in 2017.
Radar "pulses" every 5 or so seconds. Rendering it pretty much useless.
Only health drops normally. Armor Health capacity is tied to level. Pickups heal whole team, and can overheal to 150%~ of starting health.
At least one weapon of each type is "buyable" at each level. Credits seem to be the same as score. The rest can only be obtained from drops from the larger enemy types.
Trooper Armor: Nothing special, I think it might have throwing grenades as it's power.
Tactical Armor: Drops turrets that range in power, starts with a Machinegun and Plasma Mortar turret, can deploy a Radar Unit that restores the HUD Radar to it's always on status. Only has enough energy to deploy one offensive turret and the radar unit.
Battle Armor: Has a shield, covers from all sides but generally only absorbs 3-4 attacks. Can use the shield to either zap nearby enemies, or use all of their energy at once to create an explosion centered on them. Very slow while shield is deployed, but keeps up with the other land armors when it isn't.
Jet Armor: Can fly for short periods... but as all it's weapons require a section of it's energy bar to reload, it's pretty much grounded. It is the fastest armor, but I haven't leveled it much past 2, so I don't know if it manages to significantly increase it's flight time.
Assault Rifles: Still as useful as ever, though every class but Battle has tiny magazines for their guns.
Shotguns: Decent, but fall short of assault rifles.
Rockets: Really seem fubar compared to missiles. No significant increase in power.
Missiles: All seem to have the max speed and tracking powers of 2017's missiles. They also home in on the weak-points of any enemy that requires you shoot them in them.
Sniper Rifles: Seem to exist, but aren't accessable on most armors. Possibly drop only weapons.
Grenade Launchers: As useless as ever.
Ants: Two flavors, black and mechanical. Simple health upgrade...
Spiders: Two flavors, normal and mechanical. Again.
Ticks: New enemy, little running bombs. You have a couple seconds to mash Y/Triangle to get them off of you before they detonate. They seem to have dodgy hit-detection both coming and going. Battle Armor's bugzapper makes shot work of hordes of them.
"Mini" Hector: Bears a strong resmblance to a Halo Elite... Has all of the 2017 Hector weapons at all times, uses them randomly. Seems to have a weak-point on it's chest, but can be killed from any damage.
Carriers: Have two smaller drop-ports, instead of the one huge one. Elsewise same as 2017.
Bomber Spider: Huge Spider, spawns ticks while alive, and a final wave when killed. Not all that much of a threat either way.
Wasps: Normal wasps are just flying ants, they can be annoying to kill with the shitty radar making them harder to keep track of. Mechanical Wasps show up later, and occasionally divebomb/pin you and to a fairly large amount of damage. Elsewise, they're not any different from standard.
Mantis: Usually show up in twos, take a lot of damage to put down, and have some huge AoE attacks.
Hector: Sky-scraper sized Hector. Has a huge AoE ground slam, weak-point is on it's chest. More than one at a time is wave 9 of survival. Haven't seen anyone make it past that wave...
Daddy Long Legs: Huge carrier spider. Mildly reminescent of the walking fortress from 2017, but moves much faster, and you can't shoot off it's weapons.
Queen Ant: Pathetic boss fight... Shoot it's weak-points until it dies... be swarmed by ants...
Overall, it's prettier than 2017... but not much else. I'm sure the increase in graphics, more than anything is why there're fewer enemies at any one point than in the major missions of 2017.
The weapons feel like they have to reload more often, and the inclusion of an active reload makes their reload times feel punitive rather than the active reload being a reward for hitting a button at the right time... It also feels a bit dodgy, seeming to miss occasionally when dead center of the bar.
It's a solid enough game... but if you didn't like 2017, there's really nothing else here for you. And if you did like 2017, it won't recapture the spark...