One way to rebalance the game to play on a smaller surface could also simply to reduce the movement distance. For instance normal units walk 4'' and run 8'', slow units 3'' and 6'', fast units 5'' and 10''. These are similar values to warcry which is played on a 22*30 board. You could also allow to move after shooting, which enables fighters to fall back while still causing damage to the enemy. Or require line of sight to charge
Here are my longer thoughts for today on this question:
High Level Differences
Types of missions
Fixed at 4 rounds
Many missions have a variable turn length meaning you can plan your actions based on things being done round 4
Lists of units, still has some ‘groups’, no limitations on choices, other then points
Limited numbers of ‘upgraded’ units, so for example you can’t pack special weapons on all of your units.
Movement/attack & Tactics (special actions that cost points that you have a limited amount that accumulate every round)
Final round points controlled
Most missions have multiple ways to gain victory points and point control is normally calculated every round
Final wound on unit
Roll for stun or dead Stunned – loose 1-2 actions (depending on if acted this round) & another wound is automatically dead
Roll for dead or flesh wound flesh wound – 1 point penalty to most actions, including future wound roles
Phases separating out movement, Psychic, ranged, & melee
Typically only vary based on attacks, & AP and some have a special on hit
More variations/labels/etc. The biggest noticeable differences are how some interact with movement & melee combat, and rapid fire weapons which get 2x shots at 50% range (which seems to be almost all the weapons that feel week to me in GF:F – they get 2x shots at 50% range in Killteam)
I haven’t seen any abilities that come across as ambush/scout, however there appears to be a reserves rule, but that is any unit and arrival from edges, not the same as ambush. I think this is in an expansion, not the core rules.
A pre-game bluff/guess your opponents thoughts and random field effects
Faction Differences This will be focusing on a few factions based on the ones I have played [against] in GF:F and/or built armies for for Kill Team (haven’t played enough kill team yet). I going to limit my comments based on what looks like the ‘iconic’ abilities of a faction as that is what covers the what makes the faction feel like the faction.
Alien Hives This one is based on a faction that one of my son’s friends wants to play, I have mostly look these, not played yet. One of the bigger things is Synapse which is a leadership thing were some units give the weaker units a leadership buff when in range, which doesn’t appear to exist and the related Instinctive Behavior. The combination makes the weaker units reliant on a ‘Leader’ type unit to be near by to be at best performance. Given that (at least how I have seen them played on battle reports), they are a very melee focused faction, which given my prior comments about ranged vs melee (the lack of melee lock down removing ranged ability), there seems to be some impact there (I haven’t played this, so I am not 100% how this plays out).
Battle Brothers This one is one I picked up models for, haven’t had a chance to play it. These are probably the most similar as they seem to have the least ‘what make this faction different bits to them.
Human Defense Force Again, this faction is fairly vanilla, so not much that stands out, other then the commander ability. In Killteam, the commander ability is automatic, however doesn’t automatically get the AoE that is in GF:F (however there is a tactic to give that). Given the differences in behavior, I think the GF:F version of commander works as a reasonable substitute.
Machine Cult Canticles – Killteam has a list of team wide effects that can be randomly determined or chosen (but not repeated when chosen), GF:F, it is a AoE buff of +1 to hit for both ranged & melee (one that is commonly gives what would be stealth in GF:F). The other thing is that in Killteam, units (at least the ones in the book I have) all have an invulnerability save, which it looks like was done as regen on a few units in GF:F or dropped all together (which might be reasonable given the can always save on 6 – Kill team if AP pushes the save past 6, you get no save normally).
TAO Drones – are always separate units in Killteam, never upgrades to units (other then the Support Turret which is effectively an upgrade, but it gets destroyed if the upgraded figure moves more then 2” from it) Spotting Laser – they behave meaningfully different and are ‘free’ on the relevant units instead of being quite expensive. For the greater good – non-charged units can over-watch (shoot at units charging into melee) if they are close to a charged unit (basically makes it harder to charge at TAO if they are grouped up) Savior protocols – wounds can be diverted onto nearby drones
Thanks for taking the time to make this a comparison. I am a KT/40K player who has enjoyed 1P40K. I look forward trying FF.