Frostgrave - Better with a DM?

We invited one of Kyle's mates over this afternoon for a game of Frostgrave. After our initial game earlier in the week I had a few misgivings. The d20 based combat system and 'grab the treasure & run' scenarios don't quite do it for me. But (and this is important), I really want to like this game. I can see that it has a lot of potential.
So what to do? I decided to try something slightly different. Rather than play a standard game or one of the supplied scenarios I thought it would be fun to put together my own scenario for the two boys to play with me acting as Dungeon Master. This would allow Kyle and his friend to play the game without getting bogged down in the rules (simple though they are) and give me the opportunity to watch them play and see if my concerns are valid.
The short answer is that the kids had a blast, thoroughly enjoyed the game and simply didn't care about the vagaries of rolling a d20. In my role as DM, I was able to add little extras to the game to keep things moving along at a brisk pace and ensure that uncertainties over rules etc didn't get in the way of the boys simply having fun. I was also able to keep certain things hidden from the players to introduce an element of uncertainty.
So, here's what we did...

The Road to Frostgrave
Those adventurers brave enough to face the perilous road to Frostgrave will find treasures a plenty...

Set-up
The game takes place outside of the ruined city, where an ancient trackway crosses an old stone bridge.

At one end of the table is a small village. Various sacks and boxes are stored near the hovels. Outside of the village is a murky pond close to which is an area of boggy ground. A steep sided hill is located near the river on top of the hill is a large upright stone engraved with mysterious symbols. Several woods are located either side of the trackway.

The trackway crosses an old stone bridge before winding its way through marshland and then onwards to Frostgrave.
The rotting corpses of several soldiers and an old man with a long staff lie where they fell along the road. A severed arm still clutches a sword that appears to shine with an eerie blue glow... Only the old man is located on the far side of the river. His outstretched arms seemingly clawing for the edge of the road, whilst next to him is an open chest of treasure.

Special Rules
Players are heading to Frosgrave and to get there they have to cross the river and exit the table (ideally along the road, but it depends how fast they are running)! Players enter from the two table corners on either side of the village.
Of course nothing is as simple as it seems. Old bridges have stories of their own and the one in this game concerns a tortured spirit that haunts the bridge in the form of a wraith.

As soon as the first adventurer sets foot on the bridge, the wraith materialises and attacks! DMs should remember that wraiths are immune to non-magic weapons...
Clever players may realise that an open treasure chest on the far side of a bridge is too good to be true and rightly guess that the bridge may be trapped in some way. They'll enquire about wading across the river and the GM should inform them that since there hasn't been much rain, they can indeed cross the river with a half movement rate. Thinking they have outsmarted the GM the player may test the water with a soldier. As soon as the figure enters the river, the water around his feet will start to boil and a monstrous shape will loom before him...

The river is enchanted and protected by a large construct.
[I painted this old Citadel water elemental sometime around 1988 and this is the first time it's been used in a game!]
Of course pesky kids think they are smarter than wise GMs and as soon as they hear some befuddled old git muttering about low rainfall and wading with only a half movement penalty, they'll know that something is afoot.
[It was at about this point in our game when the two boys started to encourage each other to cross the stream. A smug DM even heard one of them say 'We should be helping each other not fighting"]
There are spells that allow figures to leap (and possibly other convoluted ways that smart ass kids will come up with for getting across the river without using the bridge or getting their feet wet).

A wise DM will have on hand a second large construct, this time in the form of a wind elemental that materialises mid-air and immediately attacks.
[yes this old Citadel figure was also painted in the late 80's]
Hopefully by this time the players will have stopped trying to outsmart the DM and start searching for something that can kill a wraith!
Some players may feel that battling past elementals and killing undead spirits with a pilfered magic sword is quite enough excitement for one day. However, the DM should simply smile and suggest that a thudding noise can be heard in the distance. Nervous players will by now be sufficiently unsettled that their wizards will be legging it over the bridge to escape with their plundered loot. As soon as the first figure crosses the bridge...

[remember Blood Rage? The figures are very nice! And will be even nicer once they are painted!!]
A frost giant appears from a random table edge and rushes towards the lead wizard.
Whether the DM allows the frost giant to reach the wizard depends on how tidy that particular player has kept their bedroom during the week.
[in our game Kyle used a previously summoned demon to engage the giant in melee giving the rest of his warband time to escape. Clever move!]

Treasure and Experience
The DM places 10 numbered tokens face down at suitable locations on the village side of the river.
[in our game the ten tokens were numbered 1 to 6; with several low numbers and only a single 4, 5 & 6 present]
Players are told that locations with tokens can be searched and treasure may be found. Each time a player's figure searches a location with a token, the token is turned over and the player rolls a d20 (or two d10s if you prefer...). The number on the token is added to the roll. A score greater than 20 reveals treasure. The first treasure found is a magic sword (+1 to hit). A score of 16 - 20 reveals a creature that immediately attacks. A score of 15 or less reveals nothing. DMs are advised to secretly roll for encounters before the start of the game. These can then be quickly produced from a covered box without interrupting the flow of the game. Creature encounter levels should be mostly low, with a few higher levels to keep players on their toes.
[I found it very satisfying that in today's game both players started to fear 'the box'!]
If the magic sword has not been found, it is always revealed when the last token is searched.
[To spice things up, GM's can consider revealing a creature alongside the magic sword...]
Whilst players know that tokens could be treasure, the only definite treasure item is the open chest. To get to it players must cross the river...
Experience is awarded as normal. In addition wizards gain the following experience:
15 experience points for their warband finding the magic sword
25 experience points for their warband killing the wraith
10 experience points for escaping with the magic sword.