I would like to get some feedback on how to develop a xd10 blackjack mechanic. I was thinking about using it for a spy game.

Here goes:

xd10 = to PC skill

Each d10 result represents:
1 = 1 or 11 (ACE)
2-9 = 2-9 (FACE CARD)
10 = 10 (10, J, Q, K)

PC is attempting to hack a secured computer.

GM determines opening number from 1-10. For example a 4, there some wiggle room for the PC.

PC can stake some of skill d10 to be awarded after IF the attempt is successful. For example, PC has Hacking skill of 7 and stakes 4d10 for possible bonus if successful.

GM reveals that the target number is a 15. The PC must get a 16 or higher to be successful WITHOUT going over 21.

PC rolls 3d10 getting 8, 7, 4. Keep the 8,7 and drop the 4. Final result is 15+4=19 and PC hacks into the system. Now the player gets the bonus 4 dice staked earlier.

Issues I see are, how to make the opening bid a critical element of the resolution and what exacting does the staked dice reward get you?

Now I came up with something along the lines of:

somehow the opening number must come to have more of an impact. Not sure how this would be accomplished, perhaps is the reward if successful. A higher number is more valuable, however leaves less wiggle room by the player. Or simply a random throw of 1d10 by each side, this becomes each side's opening number.

Then something like:

Lets say the initial TN for any action a PC attempts is always blackjack 21. To reduce the TN the player must bid some of his skill dice to reduce this down to a more favorable number. They first spend out of their Resource Pool and if that isnot enough they can spend skill dice.

21 = 0 (Impossible)
20 = 1
19 = 2
18 = 3
17 = 4
16 = 5
15 = 6
14 = 7
13 = 8
12 = 9
11 = 10 (Simple)

So if the player wants to lower the TN to 10 a simple task to succeed then they would need to spend 10 dice.

The TN also determines the number of d10 that the GM can use to roll AFTER the PC makes a successful roll. A chance for the GM to snatch victory from defeat by the PC at the last moment.

TN = d10
11 = 1
12 = 2
13 = 3
14 = 4
15 = 5
16 = 6
17 to 21 the GM must stand, just like blackjack rules.

PC can stake their skill dice to buy down the number of d10 the GM can roll.

For example:

Using the bid method, the PC outbids the GM with an opening number of 7.

PC has a Cool resource pool of 9 and a computer skill of 8. PC needs to hack into the security system of a top secret agency without getting caught.

PC spends 6 Cool dice (taking his resource pool down to 3). This makes the TN a 15. PC must roll between a 16-21 to be successful.

PC knows that the GM will 6d10 to roll AFTER if the PC's attempt is successful. PC decides to stake 6 (from computer skill of 8) skill dice to ensure that the GM cannot roll after. This leaves PC with 2 dice left to roll.

PC rolls 2d10, getting a 6 and 5. 6+5+7=18 and the attempt is successful. The opening number 7 becomes the reward, so the player gets back 7 cool dice spent.

Another way would be to let you roll the staked dice for refreshing and building the Cool resource pool, getting up to 21. For instance, say you staked 4d10, you roll getting a 1, 4, 6, 9. Total it and it becomes 20 Cool points you've just earned.

But not so sure if this makes it any better.

Why not just use cards?

V

Just because I prefer dice :)

In this case I'd probably have rules for both cards and dice.

How does the mechanic seem? That is what I need to hear. Can it be made better?

My first impression is how this is evocative, but complicated. What is it there for? How does a conflict look like? What does this mechanic do that your game needs? Why not simply use roll under/over or count highest or count successes?

If the PC can choose how many dice out of the ones rolled they keep, is there any real threat of going over 21. It seems the point of having a cap on rolls would be that it would intimidate the player into risking failure by choosing to roll less dice so that over 21 isn't reached. It seems like a "21" should be a critical success, and anything over 21 a critical failure. Below 21 but above the TN would be a "normal" success while anything under the TN would just be a normal failure. The benefit of a system like this would seem to be that it would add a high degree of tension and uncertainty to every roll (Oh, TN is 15, I can probably get that on three dice, but do I make it four and take the risk?). The only real problem I see with doing it like this is that it could be extremely punitive, so you might need some way to mitigate that.