There is a reason Plants vs. Zombies made such a large impression, the balance of mechanics is well designed (in addition to its charm). Each plant counters different types of zombies or gives the player different benefits meaning they must carefully decide what to plant next or they could quickly fail.
The game's biggest flaw is in its earliest stages. It is an incredibly slow game for new players. The early levels act more as tutorials for different plant types, which is perfectly sensible, however, they quickly begin to feel like a drag as they halt you from getting into the main game, something which could have simply been added to a tutorial section for those who would prefer to get into the game slowly (something which the sequel remedies).
Different zombie types are introduced to the player but their introduction is far less forced and better implemented; for example, when the Wall-Nut (a wall to stop enemies) is introduced, quickly the vaulter zombie appears which can leap over them, instantly telling the player the disadvantage of a Wall-Nut. This works well. Especially when different area types such as the Pool become available with more new plant types, specifically the Lily Pad which allows you to plant on water. Additionally, the way the game displays the progress of waves is very intuitive and uninstrusive whilst still giving good information on the player's progress.
Each plant type feels different and makes a large impact giving meaningful choice. Sunflowers being the prime example of this. The Sunflowers are an essential part of the game as they give the player Sun (the resource required to plant) after a certain amount of time. The player must decide if it is safe for them to plant these fragile units to gain a powerful resource over time or if they should strengthen their defences as best as they can before inevitable chaos.
Eventually an upgrade system is introduced using a new currency based resource which is gained by completing levels. After level 3-4 you find the key to the exuberant character, Crazy Dave's car which allows you to purchase these upgrades which inlude; New Plant Types, Seed Extensions (so you can use more plant types in one game), Specific Plant Upgrades and more. This system is well designed as it allows the player to make specific choices in what plants need the upgrades most without making too many redundant.
It is difficult to argue with the success of Plants vs. Zombies especially with it being the first of the franchise.
Cherry Bombs: A plant which costs a relatively high amount of Sun which detonates in an area after several seconds dealing massive damage to enemies. Designed to be used whenever the player is overwhelmed they often don't feel fun to use as if you are cheating as your Peashooters are mercilessly firing away at zombies this little Cherry Bomb can just wipe out every zombie in a moment.
Playing the game without using them feels better and more tactical especially when the Potato Mine is introduced which is a better designed Cherry Bomb. The Potato Mine becomes active after a set amount of time and explodes once it is attacked dealing large damage to zombies in an area.
Tutorials: As mentioned previously, the games drags a lot until you reach world 3 as it is trying to teach you about every type of plant and how to play the game instead of reserving that to good level design or a tutorial section.
The difficulty of early levels could definitely be increased as opposed to very slow levels with one or two peashooters trying to defeat one zombie. Better level design in terms of wave numbers and placements would also remedy this issue. Forcing players to think more about multiple lane placement and when to hold back in the early stages would work well when there is a low chance of failure.
A lot of the minor failings of the original game have been remedied in its sequels/updates and despite these failings Plants vs. Zombies still holds up really well and is a very enjoyable game.
What I Would Change
Plants vs. Zombies
Developed by PopCap Games and released in 2009, Plants vs. Zombies is a Tower Defense game that left a big impression on those who played it. The game received positive reception; 9.0/10 from IGN and 88/100 on Metacritic and has become a franchise selling sequels and new updates to this day.
Using a garden as their base of operations, the player must fend off a zombie invasion by planting plants using energy given by the sun. The longer the player plays the game the more options of plants they have but also more different types of zombies appear.
Does it still hold up?