Time for your basic Sonic 101. In its simplest form, Sonic 1, and pretty much all of its true sequels, are based on simple platform game rules. Reach the end of each stage by moving and jumping along the platforms and across the paths, tackling enemies and obstacles and making use of the various objects you encounter. The difference, of course, is that Sonic moves fast and the game's engine utilises acceleration and friction properties, allowing the levels to throw in all sorts of twists and loops along the paths, many of which require Sonic to be running at a certain speed so that he may pass them. There are six consecutive stages, each one being broken up into three subsections, called "acts", with a boss at the end of each third act.

You play as Sonic only, and can make him run left and right via the D-pad on the Mega Drive controller, and he'll gain speed gradually as you hold it, until reaching his maximum speed. At this point, you can make an emergency skidding stop by quickly pressing the opposite directional button. When standing still, use the up and down buttons to scroll the screen up or downwards a little to view your surroundings, and press left or right towards a wall or solid object when standing in front of it to push against it, also used to move certain objects slowly across the ground.

In this first adventure, Sonic only utilises two different methods of attack, in order to keep the game nice and simple. Two forms of the classic Spin Attack:

While standing or running, the A, B and C buttons on the Mega Drive controller all fulfill the same function; they make Sonic jump. When Sonic jumps, he always curls into a smoothly spinning ball (apart from when up against a wall sometimes, possibly due to a glitch, but it's no biggie) and will destroy most enemies on contact with them while in this form. The majority of traps however, and some parts of enemies such as their spikeballs will still cause harm regardless. The longer you hold the button for when you press it, the bigger the jump will be, so use this technique to make suitable jumps according to the obstacles you are faced with.

A more advanced maneuver is the rolling spin attack, where Sonic can launch into his offensive, spinning state while still remaining on the ground. Press the down button only while you're running to roll along the ground. This has the same effect when you hit enemies as with the jumping spin attack, and you're still vulnerable to traps etc, but it can also greatly increase your speed if you hit it at just the right time, such as on downward slopes where you can roll straight down very quickly. This is how you unlock the real speed in this game, in certain portions of levels, but if you happen to hit it at the wrong time, such as on upward slopes or along straight patches without much speed, you will slow down. When your speed is at its lowest, Sonic will break out of the roll by himself, but you can jump out of it at any time if you wish. May take some practise to perfect.

Sonic's health is controlled in an innovative way. There are no hearts or health bars, it's all handled by collectable gold rings, which you'll find all over the place, floating just above the ground or in the air. When Sonic takes a hit, he loses all the rings he's collected and they physically scatter across the area. If he takes a hit while carrying no rings, he'll lose a life, so as long as you have at least one ring you won't die when you get hit by something. When you are hit, Sonic's sprite will flash for a moment, during which time you'll be under temporary invincibility to ensure that you don't get hit again. It's a good idea to use this time to re-collect some of the lost rings that are bouncing all over the place, before they disappear. The more rings you have, the more there are to lose (and pick up again) when you get hit, thus the better chance you have of surviving. Also, every hundred rings collected awards you an extra life. You start off with three lives, and upon losing one of them, you restart the level from the last checkpoint you touched, or the beginning of the act.

Bear in mind that there are some exceptions that can kill you instantly; when you get crushed between two solid objects, drown underwater or fall off the bottom of the level, and this is regardless of however many rings or what power-ups you have at the time. Lose all of your lives and it's game over for you. Continues, however, can be obtained in the Special Stages by collecting 50 rings there. When you lose all of your lives, a continue gives you the option of picking up from the beginning of the act you were on, with a fresh new set of three.

Collectibles and other objects that directly affect certain aspects of your play.

Touch one to make it disappear, and a value of one is added to your ring count. As I've described in more detail above, rings represent Sonic's health. He loses them all whenever he gets hit, but when he gets hit without holding at least one, he'll lose a life.

Use either version of the spin attack to open up one of these item boxes which you can bounce off of on contact. Depending on the picture, you'll either get 10 extra rings, an extra life, a blue shield, a speed boost or invincibility. The blue shield surrounds Sonic and when you take a hit, you'll lose the shield, rather than any rings. The speed boost lasts for 20 seconds and will increase the speed of Sonic's movement, plus the tempo of the music. Similarly, an invincibility power-up will surround Sonic in small stars for the next 20 seconds, and he'll be invulnerable to any attack (except falling off the screen, drowning or getting crushed). Any badniks that you touch will also explode, and the music is temporarily changed to that of the main theme of the game.

Also known as point marker, starpost, etc throughout the series, but I'll be consistent and refer to them as the universal name of "checkpoint". Touch one when it's blue and your position is saved so that if you die afterwards, you'll return to that place, rather than starting from the beginning of the act. They turn red to indicate that you've already touched them or that you've already passed one that appeared later in the level, and is therefore inactive.

This signpost showing Dr. Robotnik's ugly mug can be found at the end of every Act 1 and 2. Touch one to get it spinning, where it'll eventually land on a picture of Sonic's face, and bring up the act completion procedure. This is the only way to end the act, and continue to the next one, and Sonic will automatically walk off-screen to the right after a moment. Before that, you can jump around the area and make contact with certain invisible places to earn bonuses in the form of 100, 1000, or even 10,000 points.

If you manage to complete any Act 1 or 2 (except those of the final level, Scrap Brain Zone, in which they never appear) with 50 rings on hand, a huge ring can be found to the right of the signpost. Jump in it to access one of the six Special Stages, where you'll get an opportunity to obtain one Chaos Emerald. See the Special Stage section for details.

The levels are littered with different objects to utilise, each explained on the particular level pages. Here are a few simple ones that are common across multiple levels:

Come in both horizontal and vertical forms. The verticals are used to send Sonic flying upwards when he jumps on them, and you have a certain amount of directional control, using the left and right buttons. You will not be spinning, however, so be careful of badniks and harmful obstacles on the way. The horizontals can be used as a quick speed boost across the ground, and red springs are more powerful than yellow ones.

Used in many a 2D level, in some form. Each set used in Sonic 1 consist of three sharp grey spikes that are placed a little further apart from each other than in following games, though they are more frequently arranged in a long row of sets, in deadly pits. The pointy edges are obviously harmful, but the sides are ok to touch. You need to be particularly careful in this game, because in all but one of the three slightly different versions, you won't be temporarily invincible after landing in a set of spikes, so should you stay in there when you fall back, you'll die instantly. Some also slot in and out at regular intervals.

Small blue and grey buttons found in some levels that cause something nearby to change when you land on top of them. They usually open a doorway or move a block or obstacle.

For sections where you have to go underwater, Sonic can last only 30 seconds without air. During the final 10 seconds, a countdown will begin, and you'll drown at the end of it if you don't get to the surface, or obtain some air from these bubble clusters, which are found at various points along the ground. They produce small bubbles and big bubbles, and its the big ones that give you another 30 seconds worth of air, although you may have to wait a little bit before they are produced. Just touch them to suck 'em up.