Include DLC which don't require base game

FreePackages/PackageFilter/Filterables/FilterableApp.cs

@@ -28,6 +28,7 @@ internal sealed class FilterableApp {
 		internal List<string>? OSList;
 		internal uint DeckCompatibility;
 		internal DateTime SteamReleaseDate;
+		internal bool ActivationOnlyDLC;
 		internal bool Hidden;
 
 		internal FilterableApp(SteamApps.PICSProductInfoCallback.PICSProductInfo productInfo) : this(productInfo.ID, productInfo.KeyValues) {}
@@ -57,6 +58,7 @@ internal FilterableApp(uint id, KeyValue kv) {
 			OSList = kv["common"]["oslist"].AsString()?.ToUpper().Split(",").ToList();
 			DeckCompatibility = kv["common"]["steam_deck_compatibility"]["category"].AsUnsignedInteger();
 			SteamReleaseDate = DateTimeOffset.FromUnixTimeSeconds(kv["common"]["steam_release_date"].AsUnsignedInteger()).UtcDateTime;
+			ActivationOnlyDLC = kv["extended"]["activationonlydlc"].AsBoolean();
 			Hidden = kv["common"] == KeyValue.Invalid;
 
 			// Fix the category for games which do have trading cards, but which don't have the trading card category, Ex: https://steamdb.info/app/316260/

FreePackages/PackageFilter/PackageFilter.cs

@@ -70,7 +70,12 @@ internal bool IsRedeemableApp(FilterableApp app, HashSet<uint>? includedAppIDs =
 			if (app.DLCForAppID > 0 && !OwnedAppIDs.Contains(app.DLCForAppID) && (includedAppIDs == null || !includedAppIDs.Contains(app.DLCForAppID))) {
 				// Missing a necessary app
 				// Note: Some apps have only DLCForAppid and are missing MustOwnAppToPurchase, so we need to check this also, ex: https://steamdb.info/app/41046
-				return false;
+
+				if (!app.ActivationOnlyDLC) {
+					// Some DLC can be redeemed without owning the base game, ex: https://steamdb.info/app/2765950/
+					// All I see that's special here is having ActivationOnlyDLC set to true, and missing MustOwnAppToPurchase
+					return false;
+				}
 			}
 
 			if (app.RestrictedCountries != null && app.RestrictedCountries.Contains(Country, StringComparer.OrdinalIgnoreCase)) {