Shodai Nekketsu Kouha Kunio-kun's gameplay is largely that of a beat 'em up: move from one area to the next and thump anyone who tries to stop you. Unlike most beat 'em ups the game world is somewhat free-roam; while new areas are only unlocked at certain points during the story, the available areas can be roamed at will. There is also a system of items and equipment, as well as RPG-style leveling.
- Name: Kunio (1P) or Riki (2P)
- Level (レベル): your current level
- Max HP: your maximum health, or hit points
- Max Ki: your maximum Ki points
- EXP: your total experience points
- Weapon: the weapon you have equipped. Affects your Attack.
- Lining: the lining (or armor) you have equipped. Affects your Defense.
- Shoes: the shoes you have equipped. Affects your Speed.
- Status: your condition; will be either Normal or Cursed.
- HP: your current health.
- Ki: your current Ki points.
- Power: Power, or Strength, affects your Attack.
- Agility: Agility, or Speed, affects the speed of your actions. Altered by your shoes.
- Attack: determines how much damage you deal. Altered by your weapon.
- Defense: determines how much damage you receive from attacks. Altered by your lining.
- Luck: slightly affects some aspects of the game.
Every time you level up some of your attributes will increase. Some attributes can only be increased by items.
There are very few pre-placed enemies. Most are encountered randomly. When enough characters are on the screen at once there is a high chance that they will attack you. This will cause the screen scrolling to lock, forcing you to fight it out. Sometimes one of them will aid you, and sometimes one or two will run away when the fight starts. When the fight is over you receive experience and often an item or equipment.
Sometimes you can tell when a certain group is going to attack you. In the seconds before they initiate the battle you can rush over and start thrashing one of them, meaning they'll be weaker when the battle begins.
Random encounters will be your primary source of items and experience. You can also thrash people who have not attacked you, but you get less experience from this and there is no chance of receiving loot.
One rare item you can get from the Crane Game is the Power Wrist. This weapon reduces your attack point but doubles any experience gains (except those of the Slot Machine). It only adds to the calculation at the end of the battle, which means you can defeat everyone with another weapon and then change to the Power Wrist as the last enemy falls.
In addition to equippable weapons there are some improvised weapons you can find in the environment. You can pick them up with . If an enemy is close by attacking will result in swinging the weapon; if they are out of range the weapon will be thrown instead. Weapons are automatically dropped when you enter a cutscene, and you cannot do jump kicks while carrying an improvised weapon.
- Pillow: found in several rooms of Hotel Osaka. They do little damage and break very easily.
- Megaphone: found only at Koushien. Very short range but fairly good damage and does not break.
- Wooden Sword: you can find these in Hotel Osaka, or carried by enemies. It does decent damage but breaks easily.
- Chain: slightly less damage than the Wooden Sword, but breaks less frequently. You can find these in the sewers or on random enemies.
- Trash Can: you can find these in several locations (there is one inside B1 of Hotel Osaka, and another just outside). You move slower when carrying them and you cannot jump, but it deals a lot of damage and never breaks.
- Sign Box: deals less damage than the Trash Can but slows you down less. It is also unbreakable.
- Rock: a Rock deals fairly good damage but breaks very quickly. You will often find these in the sewers.
- Briefcase: deals good damage but breaks very easily. You can often find these on enemies at Hotel Osaka and at the train platforms.
- Pipe: the Pipe does a lot of damage and only breaks after a lot of use. These are found throughout the sewers.
- Beer Bottle: these do heaps of damage but smash very quickly. You can easily find two at Umeda Umechika North.
- Car battery: very rarely found in some sewer side rooms. Deals good damage, but by the time you find one you'll probably find combos to be more effective.
- Stun Gun: extremely rare. Very occasionally found in side rooms of the Nanba-Shinsaibashi sewer by walking through the wall to the bottom right.