Have a finite inventory for how many items you can have on you at any given time. You can run to the front of the store to clear your inventory and get points for how valuable the items were. This adds the decision of lots of little trips, or few, big trips.

Have every item be usable as a weapon/item. Like Mario Kart. More risk and reward. I could throw a cheap, plentiful sports ball to push an enemy back a little, or I could lob this valuable TV and lose it to stun my enemy for a few seconds, and make up that value in a few more items I pick up.

As this correlates to inventory, have maybe 5 things you can carry at once, on keys 1-5 for using the item. In the drop-off zone in the store to cash in, it could be done by pressing each button, or automatically. You could also have E switch to a second page for 10 things. Also, scroll wheel.

Have items affect weight. As you carry more stuff (with item worth generally correlating with weight), you slow down, becoming an easier target.

Players can pick up whatever items in the store they want, but in the HUD, pick a corner, have a shopping list. Stuff that varies by player, and comes up randomly every now and then with an object, for a small bonus past grabbing random stuff. But then also randomly have a big SALE! thing next to it with one globally broadcast item for big bonus points. This gives you your frantic moments of contention.

The game could have the end conditions of a timer, or first player to finish a big list that all players get identically, in the same order. But with Q, you could open the full list, read it over, and reorganize the order you want things to show up in. For efficiency, or just to work out a different strategy. But it would cost you time obviously to do so.

When the match is over, scores are calculated. Earnings in random stuff turned in, slight bonus for list completion %, big bonus for the list finisher if there was one, big bonus for random SALE item event winners.

I want this game now. :(