Friday 5 January 2018

Simple Vector Rules - for Grav Tanks and Space Stuff

I need a simple set of drift rules for my grav tank game, as well as my PT boats/MTBs-in-space rules I'm working on.  I've already got a very good set of rules for vector movement I made years back; but the drift markers clutter the table - restricting fights to about 4-a-side before things got messy...

My design goal: minimum clutter, while imparting a feeling of momentum. Plus, ships should be able to flip and strafe sideways while drifting past enemies - because it's cool.

My current idea steals from Full Thrust only I've eliminated the need to track velocity and simplified it further. Loses a bit of granularity but I think it still feels right, and is fast - and sometimes needs no marker at all!

When moving slowly, a unit can move it's thrust in any direction. It can end up with any facing... anything goes.  For the purpose of the example I'm going to say the thrust is 4."

This gravtank, when moving at low "normal" speeds, can move anywhere in a radius = to it's thrust, unconstrained by facing etc. Like infantry do in most games.

Now this gravtank is being ambushed by a cave monster. So it wants to accelerate away and shoot backwards. The tank moves directly forward it's full thrust. When a unit moves directly forward at it's full thrust, it can opt to "drift" and use a drift marker.

The grav tank has moved it's full thrust (4" in this case) directly forward and opts for drift marker. The marker placed directly astern of the unit's base, with the arrow facing forward in the drift direction.

Now, at the start of it's next move, the ship drifts directly ahead of the drift arrow. It moves a mandatory distance - the same as it's maximum thrust. In this case - thrust is 4" - so the gravtank moves 4" directly forward. This is the "drift" stage, and occurs before all other movement.
(Luckily the tank chose to drift - the monster was closing in!)

Once the drift is done, the unit can make a "normal" move - i.e. 4" in any direction.

A ship's path is between the drift marker and it's new location (shown here by the red stick).
In this case, moving sharply to the left (where the tape and stick intersect) would be a bad move - the gravtank would smash into the wall!

Instead, the gravtank might boost 4" further forward, getting more distance between it and the monster, and pivot to shoot at it; shooting backwards while drifting the other way!  Finally, we move the drift marker towards the back of the unit's base, in a straight line.

Now, the unit's facing does not have to be the same way as the drift marker; the arrow on the drift marker dictates the drift; not the ship facing.

For example, the tank might have faced sideways to shoot a new threat. However the drift is still heading towards the wall dead ahead!  We need to stop drifting and slow down to more controllable "normal" speed.

To stop drifting, the procedure is as follows.  Next turn, you must move your mandatory drift distance like usual (=max thrust, in this case, 4"). As usual, you move/drift in a direct line in the direction of the drift marker arrow.  You then ensure the unit is facing the drift marker.

You can see the grav tank has spun to face the drift marker. This represents the unit using it's powerful rear thrusters to brake it's forward momentum. 

Having braked and removed it's 4" drift velocity, the drift marker is now removed. Voila, the unit is back in normal movement mode.

The grav tank is back at normal speed. It can now move up to it's thrust in any direction; it won't smash into the wall now!

Hmmm, so how do I feel after this playtest?


Did it remove clutter? Sure. Half the time there IS no marker (unless you are drifting).
Did it retain the "feel" of drift? Can you shoot backwards/sideways when drifting? Sure!
So it successfully met my design criteria. I'd label these rules a success.

Hardcoding the drift = thrust obviously is a bit unrealistic and loses some granularity.  
Sure, you could put a dice on the base but that means you'd pretty much permanently have to keep it there - a counter + a dice permanently goes against my "minimal clutter" policy.

Maybe you could "double boost" - i.e. follow up your first "drift" with a second full-thrust move forward to establish a 2x thrust drift (8"in this case). This would not add any clutter as you could simply use a different coloured drift marker.  You would have to spend two turns braking, facing backwards to return to normal speed....


  1. Vor some reason I would love some kind of ramming mechnik to go with that. To push enemies into walls or bring them of course while drifting.
    I would use something like this:
    If a hovertank ramms another the remaning thrust is inflicted as push back onto the target. (example: tank A hits tank B after using 2 inch of movement. tank b is moved 2 inch back in the same vector as tank a hit him.) - sheesh hope that makes sense.
    There could also be skill tests involved. Like evasion or pilot skills.

    1. No, it does make sense. If the target was larger you might reduce the say 2" thrust imparted by half i.e. 1".

      And the target could dodge with a crew check (I'm using 3+ elite, 4+ regular, 5+ rookie on d6 for most of my mechanics atm)

      Damage could be pts = to thrust; i.e. our 2" ram example could create a 2-damage hit if the tank was bounced off the wall, and an additional hit from the collision itself....

  2. Glad to see some new posts!
    Your new rule has the Battlezone vibe indeed. I hope you will push the homage further (with resource control for exemple)
    I might borrow your inertia rule, yu've found a nice spot between realism and playability!

    1. You could track drift more accurately with a d6 dice atop the drift marker to show precise velocity; but you would need to have the drift marker and dice always there.

      I'd do it that way if I was using less ships (i.e. 5-6 or less per side)

  3. It seems that there is a top speed?

    How would you encode for acceleration which continues to increase speed? Would you need to have a permanent set of drift markers indicating that velocity persists?

    1. You are correct. There IS a top speed (i.e. double thrust aka drift + thrust). A 4" thrust ship could move 8" max.

      I am content with this, for simplicity's sake. If it bothers you, you could say this is the maximum "safe" velocity to brake/avoid asteroids etc.

      However, by using different coloured drift markers, you could extend it to 3x, 3x,5x thrust etc.

      I just deemed it not worth the effort as game-wise there is little need for faster ships as the time to brake means higher speeds are impractical anyways. I.e. a 5" thrust ship, moving at 20", would have to travel 20"+ 15" + 10"+ 5" = 50" or 4ft (most of your table) to come to a stop; and if you include accelerating from 0 (50") - it could actually not reach those speeds on the table unless it was over 8ft long.

      So the 5" thrust, 10" max velocity is much more sensible from a gaming sense.

      Remember, my design brief was the "feel" of momentum and drift, with little to no clutter. No emphasis on realism (I've done more complex and realistic versions before if you look up the original Delta Vector game, but found it limited me to 3-4 ships per side due to clutter)

  4. Commenting on my earlier comment.

    I think that if you take the vector mechanism you've just described, it has top speed. This would not exist in space (it could ... but it shouldn't).

    However; your vector mechanism is something which could exist thematically within a fluid environment such as underwater! I think you've got something which could serve as your unique way of performing movement actions for SuperCAV.