We used secret objectives and missions extensively for pick-up games of various genres. Depending upon who you are playing with they can be a real hoot.
For instance: played a game of Full Thrust with some added rules (which I will be using for a convention game with 3′-6′ long ships in somewhat 15mm scale) including boarding and shipboard fighting. Each side drew a card at the start of the game for main mission, and 2 cards for secondary missions. Side A had the main mission of capturing the commander of the enemies largest ship as he is a war criminal wanted for trial. Secondary objectives were to destroy any enemy logistics ships and to push a scout type ship to exit the enemies side of the board. Side B had the mission of destroying any enemy ships that carried secondary craft (fighters, shuttles, dropships), with the secondaries of capturing the enemy command ship and scanning all enemy ships for intel.
we had 3 players on a side, each side chose their fleet from a pool of “ready available” ships, and side B found they only had 2 small ships that could act as scouts, while Side A had 1 ship that was “fast”. The game was bonkers, with both sides basically tying their command ships together for a seasaw board/counter-board action while side B ran their scouts around with a herd of defending destroyers trying to protect them. At the same time Side A was trying to keep their 2 carriers away from the scout thinking is was some sort of suicide boat while picking off the destroyer screen.
At one point both command ships has enemies aboard, and Side A had their engines destroyed and Side B had their FDC, Screens, and soem batteries trashed by marines. In the end, Side A lost 1 of 2 Lt Carriers, got their scout across (he almost made it unscathed but decided to try a strafing run against the enemy command ship and lost his weapon to show for it!) and killed the enemy CO instead of capturing him. Side B Scanned everyone and killed 1 enemy carrier, but lost 5 destroyers and their command ship, giving side A the win.
We do this sort of thing even with WW2. We’ve had games where one sides objective was to kill as many enemy tanks as possible, break their tanks through the line and exit, totally reduce the enemy infantry, take and hold a specific house (or defending said house) for 3 turns before withdrawing, punch at least 1 tank through the enemy defenses and keep it there for 1 turn before withdrawing, assault an enemy position and capture some enemy… not only keeps games fresh but also keeps your opponent on their toes trying to figure out what is going on and why their opposition is doing something that seems to make no sense. Can be a really good time, but we have had a couple of games where both sides had missions that they both completed easily with very little action and gave a sort of anti-climatic game.
"I saw this in a cartoon once, but I'm pretty sure I can do it..."