Find a route to the Hall of Heroes is a mission in Ratchet & Clank. After Ratchet and Clank destroy the blarg warship and defended the Hall of Heroes in Aleero City on Kerwan, they were recruited to the Galactic Rangers. They were set to train with Brax Lectrus in the Hall of Heroes afterwards, though their ship was then destroyed by a blarg commander, causing them to fall below to Downtown Aleero City. This required them to find a route back, though a few blarg from the attack had remained in the city, missed by the Rangers during their sweep of the perimeter. Cora Veralux recommended they speak to Al along the way, the man in charge of a roboshack, for upgrades for Clank. Al provided the Helipack for free.
When first arriving, head through the tunnel and down a bridge to the Gadgetron vendor. Mr. Zurkon is available here for 8,000 bolts, a robotic bodyguard for Ratchet that follows him and attacks nearby enemies, providing supplementary firepower. Mr. Zurkon is a useful weapon, though it might not be affordable at this stage, and the Proton Drum should be prioritized. Purchase any available Raritanium upgrades and then move on.
In Kerwan, you will encounter four enemies: blarg troopers, blarg commanders, blarg heli-commanders, and robomutts. Blarg troopers are familiar, while blarg commanders are larger, beefier blarg, which fire lasers with a faster rate of fire, and will punch Ratchet if close, and are best defeated using the Combuster or the Fusion Grenade. Robomutts are small robotic dogs which charge towards Ratchet, and best defeated with the Proton Drum if available to throw one in front of Ratchet and destroy them before they reach him, but can be instantly defeated with any weapon. Blarg heli-commanders are blarg attacking with deadly lasers from helicopters, and the best option is to dodge the lasers by strafing while throwing Fusion Grenades or using the Combuster to defeat them. Make sure you jump and strafe often or run behind objects to avoid the lasers from the heli-commanders or commanders.
From the Gadgetron vendor after the tunnel, head down the steps to the right and follow a mostly linear path through skybridges across buildings, defeating all the enemies along the way. You will reach a building with a set of stairs down to a small fountain, and finally to a skybridge leading to Al's roboshack. Outside the roboshack, destroy the blarg commanders, troopers, and heli-commanders, then hit the green button next to the roboshack door, and it will open up allowing you to enter. Al will provide Clank with the Helipack, which can be used by pressing while stationary to boost jump upwards, or while running to stretch jump forwards. Make sure to use the vendor here to restock on ammo.
After this, Al will provide you the next mission, "Find a train to the Hall of Heroes".