You can either pay 3000 Gil each time you visit the Gold Saucer, or pay 30,000 Gil for the Key Item "Gold Ticket", which is a lifetime membership; meaning after obtaining it you never have to pay entry fees again.
Be aware that in order to use the Save Point at the entrance to the Gold Saucer, you will have to spend 5 GP.
Depending on how you play the game up until the point where you stay overnight at the Gold Saucer after obtaining the "Keystone" Key Item, you can go on a date with either Aeris, Tifa, Yuffie or Barret.
Most likely the date will be with Aeris or Tifa; but if you end up dating Barret, you will earn the "Best Bromance" trophy/achievement in more recent versions of the original game (e.g. the Steam or PS4 download).
For details on how to go about earning Best Bromance, take a look at this guide on psnprofiles.com.
Main Chocobos Guide here!
In the Chocobo Square, you can either gamble on the outcome of Chocobo Races, or take part in Races yourself using your own chocobo.
There are 4 Classes of Chocobo Races - S Class, A Class, B Class and C Class. S tends to give the best prizes, followed by A, then B, then C.
You can only gamble on S Class Races once you have reached S Class with one of your own chocobos. To do this, go through Classes C then B then A. Winning 3 times at Class C takes that chocobo up to Class B; then winning 3 times at Class B, then 3 times at Class A, takes the chocobo up to Class S.
An effective technique when betting (rather than racing) is to pick 3 chocobos and bet on just those 3; or pick 1 chocobo and select 3 bets featuring that chocobo. E.g. pick chocobos 2, 4 and 5 and bet on "2-4", "2-5" and "4-5"; or pick chocobo 1 and bet on "1-2", "1-3" and "1-6"
Chocobo racing is one of the fastest ways to earn GP in the game, and also earns you items and materia which you can't get anywhere else - i.e. Cat's Bell accessory, Chocobracelet armor, Precious Watch armor, Sneak Attack materia, and Enemy Away materia.
It costs 10 GP to enter a battle in the Battle Square - you must earn GP elsewhere in the Gold Saucer. You can win very powerful items here which aren't obtainable anywhere else, i.e. Final Attack materia, W-Summon materia, Omnislash limit break, Champion's Belt accessory, Speed Plus materia, Pre-Emptive materia, Enemy Lure materia.
Once you've obtained W-Summon and Omnislash, as well as having the "Ultima Weapon" sword for defeating Ultimate Weapon, you can enter a "Special Battle". The prize for winning this is the Final Attack materia, one of the most powerful materia in the game (Materia Guide).
You can also win various items which are essentially useless apart from filling up your inventory, i.e. Tissue, Autograph, Combat Diary, Gambler.
Taking part in either the normal or special battle sees your party member fighting against up to 8 rounds of enemies. The more enemies you defeat, the more Battle Points (BP) you will earn. After each round, you will spin slots to determine what handicap you will have going forward.
The most effective technique is to make Cloud powerful in different ways, such that he is still able to win all 8 battles even with heavy handicaps ("Jack of All Trades"?). So you will want to give him a Ribbon, Mystile armor, Ultima Weapon, powerful Commands (e.g. Double Cut, mastered Enemy Skill materia), powerful Magic (e.g. Master Magic-All Materia), powerful Summons (e.g. Knights of the Round), powerful independent materia (e.g. multiple Counter Attack materia) and powerful items (e.g. Elixirs, Hero Drinks, Remedies). Note that it is not a good idea to use the "Resist" magic from a Heal materia to protect against status abnormality; if for example you get turned into a frog by the slots, the game glitches if you have cast Resist, and you end up not only turning into a frog but also being unable to remove the abnormal status, i.e. you are stuck as a frog. Equip a Ribbon instead.
The more battles you complete, the more BP you stand to win. The main handicaps which earn you a large number of BP (generally over 10,000 at a go) are Weapon broken, Armor broken, Accessory broken, and any or all Materia broken. N.B. As far as I can tell, these main handicaps must be implemented on exactly the 7th slots roll (just before the last battle). Any other handicaps on the 7th slots roll and you're likely to only earn around 4000 BP.
There are 2 more things to be aware of. Losing a battle loses you the BP you have won up to that point; but only the BP you could have won in an attempt in the Arena. E.g. you obtain 12,000 BP, accumulate 1000 BP by the end of the 7th battle, but then lose the 8th battle - you would still have the 12,000 BP; but you lose the 1000 BP.
You can swap BP for items. Remember to do this before leaving the Battle Square. There follows what you can obtain. Note that prizes and "cost" of prizes change somewhat depending on where you are in the story.
Before getting the "Tiny Bronco" vehicle:
After obtaining Tiny Bronco vehicle, before obtaining Highwind vehicle:
After obtaining Highwind vehicle:
N.B. Most of the prizes can be obtained multiple times; but you can only earn Omnislash, W-Summon and Final Attack once each.
If you complete all 8 battles in a row on Disc 1, the woman outside at the front of the Battle Square will give you a "Sprint Shoes" accessory if you talk to her.
It costs 10 GP to have a go at the Speed Square. Obtaining at least 5000 points on Disc 1 wins you the unique "Umbrella" weapon for Aeris; obtaining 5000 points or more on Disc 2 or Disc 3 wins you the unique "Flayer" weapon for Cid. Note that you can only win one of each of these at most.
It will probably take quite a lot of practice to obtain 5000 points. One tip I can give is to make sure you destroy the UFO near the end (this gives you 1000 points); to do this, use several short shots of your laser. In general it is more effective to use short shots rather than holding down the "Shoot" button; the exception is on the boat about half-way through; if you hold down the "Shoot" button on the rotating water wheel part of the boat, you can build up points quite quickly. Destroying the moving spotlights near the end gets you 200 points each.
You can also win various mostly useless items here by obtaining either at least 3000 or at least 5000 points, i.e. Super Sweeper, Masamune Blade, 1/35 Soldier.
In the Wonder Square, you can obtain GP by taking part in various activities. For example, achieving over 10,000 points at the G-Bike game gets you 10 GP. Generally speaking, it is much, much simpler to use the Chocobo Square to build up large amounts of GP.
There is a Trophy, "COREL'S ANGEL", for scoring over 10,500 points at G-Bike in more recent versions of the original game, however...
You can exchange GP for prizes at the Wonder Square - it's the only way in FFVII of getting the "Gil Plus" materia (for 1000 GP) and "Exp Plus" materia (for 2000 GP). You can also obtain the "Gold Ticket" Key Item here for 300 GP, rather than buying it at the entrance for 30,000 Gil.
The Mog House game is a quick and quirky way of earning 30 GP for only 100 Gil. You have to feed Mog Kupo Nuts to help him fly. Feed 5 Kupo Nuts the first time, and 3 the second time, to win the game (Mog will do a "happy jump" when given the right number). Then talk to the man watching; he will give you 30 GP.
Finally, there is a random chance of a man appearing at the top of the screen at the Gold Saucer entrance. You can bribe him into giving you GP at 100 Gil for 1 GP; you can spend up to 10,000 Gil at a go which would earn you 100 GP. The man will never stop reappearing, but the chance of him being there is only around maybe 1/5 each time you visit the entrance. Gold Saucer Management firmly deny any knowledge or association with the individual concerned.
For further Gold Saucer help, I recommend Jegged.com's excellent guide.
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Limit Breaks Guide
Enemy Skill Guide
Items Winnable from Battles Guide
Enlisting Yuffie and Vincent
Wall Market Cross-Dressing Guide
Turtle's Paradise Flyers Locations
Shinra Building Floor 62
Shinra Building Floor 63
Junon Parade Guide
Gold Saucer Guide
Huge Materia Rocket Code
Alexander & Added Cut Materia
Materia Selling Guide (make loads of Gil)
Emerald Weapon & Ruby Weapon
About the Characters
List of Every FFVII Title
Other FFVII Websites