I have all of the BattleForce games.
BF-1 was weird. It can basically be described as four mechs blended together/averaged, then printed onto a small game shield with full stats, 3/4 damaged, 1/2 damaged, 1/4 damaged, and no need for zero as it was dead. You keep the little game shields facing you at all times so the enemy player cannot see your stats. Facing was unnecessary. Did I mention these little game shields with the stats printed on the backs are you hexmap playing pieces? Yeah, not a fan.
BF-2 I don't really know that well. I do own it, but never played it. It does have the familiar stats similar to Alpha Strike. However, short range is the same hex, aka 0 hexes, medium range is 1-4 hexes, and 5-8 hexes is long range. Except they call it Point Blank, Medium, and Long. I think Aerospace fighters just move in a straight line, period. To turn, you wait until next turn, pick a direction, and go in a straight line up to maximum thrust. Also, the game has all the stats for all the units in the back of the book, so no need to look it up online or buy cards. However, you move a full lance as the smallest playing piece. The difference between BF-1 and -2 is that this time the units are treated individually. They all move together as a group, pick another enemy lance to attack as a group, but are individual mechs and such when it comes down to it.
BF-3 is found in the Strategic Operations rulebook. It is actually like BF-2 by quite a bit. Some of the ranges change slightly. Short range is now 0-1 hex, medium range is 2-4 hexes, and long range is 5-8 hexes. The other big change is that Aerospace Fighters now can turn after traveling "X" amount of hexes when flying over the ground terrain map. In Space it is a different, much shorter scale. Overall, it seem just a marginally changed game over BF-2.
And then we get to Alpha Strike. The 3 major changes are: 1. The range of weapons are MUCH longer. 2, the units are no longer groups of 4 mechs as a single lance. Now, granted, in BF2 and BF3 track each mech separately, just not for movement. They move as lances. 3rd, the game is re-rigged to be hex-less. The default way to play is on a model table using tape measures or rulers.
Overall, I think BF-2 and BF-3 are still viable games. However, Alpha Strike is the current version of BattleForce.
Why the name change? Probably a marketing thing. Renaming it makes it seem like a new game, when really it is the 4th BattleForce game.