In the ServerPluginList value of the Server section in your gg2.ini, write upgradeable_sentries to use this plugin. Additionally, change your ServerPluginsRequired value in the same place to 1, since this plugin is incompatible with clients that don't use it.
Standing next to a level 1 or 2 sentry with Nuts 'N' Bolts drains Nuts 'N' Bolts, but eventually upgrades the sentry. Credit for the sprites goes to someone that I can't remember. Waterfall, maybe? If you know who, you should tell me. I've had them on my computer for so long that I forgot who made them.
-Sentries have been given knockback so that they can't be completely maimed by a scout that decides to tank their shots and jump in their blind spot.
-100 NNB to upgrade 1 level, max level being 3.
-Level 1 sentry is unchanged damagewise.
-Level 2 sentry shoots twice as fast as level 1, with the same damage.
-Level 3 sentry shoots as fast as level 2, shoots rockets, and deals 120% damage per shot.
Lorgan is a sweetie that has my kisses forever.
Conflicts with anything that changes the Begin Step event of Sentry or the End Step event of SentryTurret (This does not include the dispenser plugin when it is made, however, because I will ensure that the two plugins are compatible.)