Since the guy basically disappeared from around here, I'll post a summary of this discussion's salient points that the user Isaac Springsong wrote for the "megathread section" but never bothered publishing. Leaving it buried as a "work in progress" seems a bit of a waste. I arbitrarily omitted just a point he made about "making a grid based on bigger squares" because I fundamentally disagree with it.
Summary: The Chain/unchain mechanic feels clunky and often doesn't provide a good sense of party control during movement. It requires too much micromanagement and often results in party members moving into surfaces or other unintended areas. Players would prefer the standard cRPG selection methods (mouse click + drag, party formations, ability to set formation facing on movement, singe click to select/deselect or shift select/deselect).
Chain/unchain - This method of party selection creates several problems. Some mechanical, some thematic. The first is that it takes too long to choose which party members you want to move. This only gets worse as the party size gets bigger. Say your party is entirely selected, but now you only want to move two of them together. That now requires you to:
1. Click on one party member's portrait, dragging it far into the screen, and then rotating the cursor and releasing. This *might* separate the party member.
2. Repeat step 1, but for the other party member.
3. Click one party members portrait and drag it 'next to' the other party member and pray that they snap together.
That method is far too imprecise and often takes several seconds of trying to get nearly pixel perfect mouse dragging. Moreover, it makes for numerous situations where you are trying to do simple movements, but can't do so without multiple clicks and dragging portraits to create new groups. See the Jumping problem below for one such example.
Possible Solutions - Honestly just go play the original BG series, Neverwinter Nights, Pathfinder Kingmaker, Wasteland 3, Solasta, pretty much every other cRPG system. It was a great idea to try something new in DoS 1 & 2, but this topic has near universal agreement to use the standard party selection methods. Be able to click and drag a box around party members to select them. Be able to shift + left click to select party members. Be able to shift + keypad number for party member (i.e. Shift + 1 + 2 makes you select party members 1 and 2 together).
[**]Jumping - It is *very* frustrating that you have to individually select each party member and give them jumping instructions. This is magnified by the fact that you also need to move each party member after jumping to create enough space for the other members, except then you also need to unchain everyone because otherwise party members on the destination side will randomly run around, taking up precious landing space, as the chained movement system requires. During world exploration (out of combat), each party member should just follow the leader and automatically jump to follow the leader of their group.
[**]Sneaking - Can't have sneaking members follow one another. Either everyone sneaks as a chained group, or you have to do each character individually. This is cumbersome if you only want 2-3 party members to sneak together.
[**]No formation facing - Formation facing is extremely useful for careful placement and knowing where each party member will end up at the end of the move. This is crucial when you are moving near traps or other interactable environmental effects.
[**]Bad Pathing - Related to the above, the pathing system in the game is bad. Party members often double around obstacles the player didn't know was there, run straight through easily avoidable surface areas, and generally feels clunky. A lot of this is related to characters occupying 'more space' than they should by the rules, and by character models not being able to move through one another.
[**] Small Movements = Disaster - Right now, moving a chained party member causes the other party members to go crazy, shifting their positions back and forth and often triggering traps, encounters, surfaces, and just generally looking silly. There should be some leeway in moving a group's 'leader' (whomever the player has selected) without it causing the other party members to adjust their position (unless using something like formation facing so as to allow the player to also move the group in small increments). This is a great example of why this is bad ->
Possible Solutions - Much as the first suggestion, not need to reinvent the wheel. Which is ironic because right now the movement system is like trying to steer a car without a steering wheel. Technically possible, but no one wants to do it. The movement system of DoS 1 & 2 was thoroughly cited as one of the detrimental parts of the game. BG 3 somehow made it worse. It's time to let it die and adapt the movement schemes used by every other cRPG.
Miscellaneous: I cannot stress enough how much the party selection and movement system exacerbates the "This game is just DoS 3, not BG 3" problem. The schemes used in BG 3 are only used elsewhere in DoS 1 & 2, nowhere else. If the schemes were good, they'd have been adopted by other games. Changing how the player interacts with their party and moves them throughout the world to more closely resemble the original series (as well as the derivative games that were clearly inspired by BG) would go a long way towards making BG 3 both a clearly distinct product from the DoS series and make it feel more like a spiritual successor to the BG series.
I'll also add this to the OP. It's probably a better summary than my half-assed original incipit. EDIT- Nevermind. I can't edit old posts apparently.