I'm not loving what I'm reading in the rulebook for that other game that uses the TacDice system. I know Tactics won't be exactly the same as Schlock Mercenary, but the basic movement and combat system are probably very similar. In Schlock Mercenary:
1) You roll dice to see how far you can move, which I don't love. That means that how far you can move is random turn-to-turn, which makes actual tactical choices more difficult.
2) When you roll dice for movement (or for how many command actions you can take on a turn), you'll either use the highest of the die results, the lowest, or the middlest (median) result, depending on the situation or your powers, or whatever. This seems to be a core part of the TacDice system, but it doesn't actually seem to be a particularly clever or good system. It's just a different one.
3) For combat, each attack lists the number of dice you roll, and has an auto-miss number(s). The example they give is for a Laser Gun that rolls 3d and has auto-miss numbers of 1 and 3. That means that if any of the die come up 1 or 3, you'll toss those die out from your results. What a random rule.
4) After you've tossed out your auto-miss dice, you then check for line-of-sight (I think I'd want to have done this before bothering to roll), and then you have to toss out any of your remaining dice that are less than the range to your target (i.e. if they're 3 spaces away, you'll toss out any 1s or 2s you rolled. Since you already tossed out the 1s and 3s due to auto-misses, you will now only have 4s or above left, if anything).
5) The defender then gets to roll some defense dice, with each one eliminating an attack die that matches it or is less than it.
6) If there's anything left over, it's applied as a hit on the target.
Here's an example from the rulebook:
Example I
Schlock shoots at a Drone and rolls 5 dice at Range
2. Schlock gets a 1,1,2,3,3. The 3s are AutoMisses
and are removed in Attack Step D. The 1s fail to
make Range and are removed in Attack Step E. This
leaves Schlock with a single Attack Die of 2.
The Drone’s Defense Attribute is 2. The Drone rolls
2 Defense Dice and gets a 1 and a 4. The Drone’s
player uses his Defense Die that shows a 4 to
eliminate Schlock’s Attack Die of 2. Schlock has no
remaining Attack Dice.
Example II
Had Schlock been at Range 1, he would have hit with
a 1,1, and 2. The Drone’s Defense Die of 4 would
eliminate the 2, and the Defense Die of 1 would have
eliminated one of Schlock’s dice that showed a 1.
This would have left Schlock with a single Attack
Die of 1.
I have to say, it doesn't sound like a good system at all. :(